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Mathematics
WAEC / WASSCE 2023
Number Bases
Solution
Arrange the following in ascending order of magnitude \(110_{two}, 31_{eight}, 42_{five}\)
A
\(110_{two}, 31_{five}, 42_{eight}\)
B
\(42_{five}, 110_{two}, 31_{eight}\)
C
\(42_{five}, 31_{eight}, 110_{two}\)
D
\(110_{two}, 42_{five}, 31_{eight}\)
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
Converting each number to base 10
\(110_{two} = 1 \times 2^2 + 1 \times 2^1 + 0 \times 2^0\)
= 1 \times 4 + 1 \times 2 + 0 \times 1
= 4 + 2 + 0
= \(6_{ten}\)
\(31_{eight} = 3 \times 8^1 + 1 \times 8^0\)
= 3 \times 8 + 1 \times 1
= 24 + 1
= \(25_{ten}\)
\(42_{five} = 4 \times 5^1 + 2 \times 5^0\)
= 4 \times 5 + 2 \times 1
= 20 + 2
= \(22_{ten}\)
Hence, \(31_{eight} > 42_{five} > 110_{two}\)
In ascending order, \(110_{two}, 42_{five}, 31_{eight}\)
Source: WAEC / JAMB / NECO Classroom Archive (Record #69124)
Mathematics
WAEC / WASSCE 2023
Indices
Solution
Solve \(2^{5x} \div 2^x = \sqrt[5]{2^{10}}\)
A
\(\frac{3}{2}\)
B
\(\frac{1}{2}\)
C
\(\frac{1}{3}\)
D
\(\frac{5}{3}\)
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
\(2^{5x} \div 2^x = \sqrt[5]{2^{10}}\)
applying the laws of indices
\(2^{5x - x} = 2^{10(1/5)}\)
\(2^{4x} = 2^{10(1/5)}\)
\(2^{4x} = 2^2\)
Equating the powers
then 4x = 2
therefore, x = \(\frac{2}{4}\) = \(\frac{1}{2}\)
Source: WAEC / JAMB / NECO Classroom Archive (Record #69048)
Mathematics
WAEC / WASSCE 2023
Logarithms
Solution
Solve: \(log_3 x + log_3 (x - 8) = 2\)
A
8
B
6
C
9
D
7
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
\(log_3 x + log_3 (x - 8) = 2\)
\(log_3 x(x - 8) = log_39\) since 2 = \(log_39\)
\(log_3\) cancels out
⇒ x(x - 8) = 9
⇒ \(x^2 - 8x = 9\)
⇒ \(x^2 - 8x - 9 = 0\)
⇒ \(x^2 - 9x + x - 9 = 0\)
⇒ x(x - 9) + 1(x - 9) = 0
⇒ (x - 9)(x + 1) = 0
⇒ x = 9 or x = -1
Since we can't have a log of negative numbers,
∴ x = 9.
Source: WAEC / JAMB / NECO Classroom Archive (Record #69168)
Mathematics
WAEC / WASSCE 2023
Surds
Solution
Simplify \(3\sqrt{12} + 10\sqrt{3} - \frac{6}{\sqrt{3}}\)
A
10\(\sqrt{3}\)
B
18\(\sqrt{3}\)
C
14\(\sqrt{3}\)
D
7\(\sqrt{3}\)
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
\(3\sqrt{12} + 10\sqrt{3} - \frac{6}{\sqrt{3}}\)
= \(3\sqrt{4\times3} + 10\sqrt{3} - \frac{6}{\sqrt{3}}\)
= \(6\sqrt{3} + 10\sqrt{3} - \frac{6}{\sqrt{3}}\)
treating like a fraction, then
= \(\frac{18 + 30 - 6}{\sqrt{3}}\)
= \(\frac{42}{\sqrt{3}}\)
rationalizing
= \(14\sqrt{3}\)
Source: WAEC / JAMB / NECO Classroom Archive (Record #68987)
Mathematics
WAEC / WASSCE 2023
Fractions, Decimals, Percentages & Approximation
Solution
Evaluate, correct to three decimal place \(\frac{4.314 × 0.000056}{0.0067}\)
A
0.037
B
0.004
C
0.361
D
0.036
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
\(\frac{4.314 \times 0.000056}{0.0067}\)
\(\frac{0.000242}{0.0067}\)
= 0.036 ( to 3 decimal places)
Source: WAEC / JAMB / NECO Classroom Archive (Record #69033)
Mathematics
WAEC / WASSCE 2023
Fractions, Decimals, Percentages & Approximation
Solution
A student measured the height of a pole as 5.98 m which is less than the actual height. If the percentage error is 5%, find correct to two d.p the actual height of the pole.
A
6.29m
B
7.67m
C
7.18m
D
6.65m
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
%error=5%, measured height = 5.98m
let the actual height = y
error=x - 5.98 (since 'y' is more than 5.98)
%error = \(\frac{error}{actual height}\times 100%\)
5% = \(\frac{y - 5.98}{y}\times 100%\)
\(\frac{5}{100} = \frac{y - 5.98}{y}\)
5y = 100(y - 5.98)
5y = 100y - 598
5y - 100y = - 598
-95y = - 598
y = \(\frac{-598}{-95}\)
y = 6.29m( to 2 d.p).
Source: WAEC / JAMB / NECO Classroom Archive (Record #69076)
Mathematics
WAEC / WASSCE 2023
Fractions, Decimals, Percentages & Approximation
Diagram
Solution
What percentage of the students scored at most 5 marks?
Attached Figure / Diagram
A
58.5%
B
63.2%
C
38.3%
D
41.5%
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
Number of students that scored at most 5 marks = 12 + 1 + 9 + 6 + 3 = 31
% of student = \(\frac{31}{53} \times 100%\) = 58.5%
Source: WAEC / JAMB / NECO Classroom Archive (Record #69153)
Mathematics
WAEC / WASSCE 2023
Fractions, Decimals, Percentages & Approximation
Solution
The price of a shoe was decreased by 22%. If the new price is $27.3. what is the original price.
A
$62.30
B
$42.30
C
$72.00
D
$35.00
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
Let x = original price
A decrease of 22% = (100-22)% = 78% of the original price.
78% of x = 27.30
= \(\frac{78x}{100} = 27.30\)
78x = 2730
then, x = \(\frac{2730}{78}\)
x = 35
Therefore, the original price of the shoe was $35.00.
Source: WAEC / JAMB / NECO Classroom Archive (Record #69166)
Mathematics
WAEC / WASSCE 2023
Fractions, Decimals, Percentages & Approximation
Solution
A notebook of length 15 cm was measured to be 16.8 cm, calculate, correct to two d.p, the percentage error in the measurement.
A
12.00%
B
11.71%
C
10.71%
D
11.21%
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
Error = 16.8 - 15 = 1.8cm
% error = \(\frac{error}{ Actual value}\times 100%\)
= \(\frac{1.8}{ 15}\times100%\)
= \(0.12\times100%\)
= 12.00%
Source: WAEC / JAMB / NECO Classroom Archive (Record #69174)
Mathematics
WAEC / WASSCE 2023
Sets & Set Operations
Solution
There are 30 students in a class. 15 study woodwork and 13 study metal work. 6 study neither of the 2 subjects. How many student study woodwork but not metal work?
A
13
B
11
C
5
D
9
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
Using the venn diagram above
\mu = 30
n(W) = 15
n(M) = 13
\(n(W ∪ M)^1 = 6\)
Let x = number of students that study both woodwork and metalwork
i.e. n(W ∩ M) = x
Number of students that study only woodwork,\(n(W ∩ M^1)\) = \(15 - x\)
Number of students that study only metalwork, \(n(W^1 ∩ M)\) = \(13 - x \)
Bringing all together,
\(n(W ∩ M^1)\) +\( n(W^1 ∩ M)\) + \(n(W ∩ M)\) + \(n(W ∪ M)^1\) = \(\mu\)
∴ (15 - x) + (13 - x) + x + 6 = 30
⇒ 34 - x = 30
⇒ 34 - 30 = x
∴ x = 4
\(n(W ∩ M^1)\) = \(15 - 4 = 11\)
∴ The number of students that study woodwork but not metalwork is 11.
Source: WAEC / JAMB / NECO Classroom Archive (Record #68936)
Mathematics
WAEC / WASSCE 2023
Sets & Set Operations
Solution
a. M = {n: 2n - 3 ≤ 37} Where n is a counting number. i). write down all the elements in M.
ii. If a number is selected at random from M what is the probability that it is a:
(α) multiple of 3;
(β) factor of 10.
b. A shop owner gave an end-of-year bonus to two of his attendees, Kontor and Gapson in the ratio of their ages. Gapson's age is one and a half times that of Kontor who is 20 years old. if Kontor received Le 200,000.00, find: i). Find the total amount shared.
ii. Find Gapson's share.
medium Difficulty
Verified Correct Answer: Option
Step-by-Step Mathematical Solution
ai. To find all the elements in the set M, we have to solve the inequality.
2n - 3 \le 37
2n = 37 + 3 = 40.
2n \le 40
n \le \(\frac{40}{2}\)
n \le 20
so, the set M contains all positive numbers n such that n is less than or equal to 20
Therefore, set M elements are {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}
(\alpha)
Pr(multiple of 3) = \(\frac{multiples of 3}{ Total number of element in M}\)
But the multiples of 3 in set M are = {3, 6, 9, 12, 15, 18} = 6
ஃ Pr(multiples of 3) = \(\frac{6}{20} = \frac{3}{10}\)
(\beta)
Pr( factors of 10) = \(\frac{№ of factors of 10}{ Total № of set M elements}\)
factors of 10 in set M = { 1, 2, 5, and 10} = 4
ஃ Pr( factors of 10) = \(\frac{4}{20} = \frac{1}{5}\)
bi. Let the total amount shared = y
Gapson's age = \(\frac{3}{2}\times Kontor's age\). Since kontor is 20yrs old then Gapson's age = \(\frac{3}{2}\times20\) = 30years.
sharing ratio = 20 : 30 = 2 : 3
total ratio = 2 + 3 = 5
Since Kontor received Le200,000
\(\frac{2}{5} \times y\) = 200,000
\(\frac{2y}{5} = 200,000\)
cross multiplying, we have
2y = 5 x 200,000 = 1000,000
y = \(\frac{1000,000}{2}\) = 500,000.
ஃ Total amount shared = Le500,000.
ii. Gapson's share = Total - kontor's share
= 500,000 - 200,000 = Le300,000.
Source: WAEC / JAMB / NECO Classroom Archive (Record #69312)
Mathematics
WAEC / WASSCE 2023
Mathematical Logic
Solution
Consider the statements:
p: Siah is from Foya.
q: Foya is in Lofa.
Write in symbolic for the statement: "If Siah is from Foya, then Foya is in Lofa"
A
~q ⇔ p
B
q ⇒ p
C
p ⇒ q
D
p ⇔ q
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
The symbolic form for the statement "If Siah is from Foya, then Foya is in Lofa" is:
p ⇒ q
This is read as "p implies q". It means that if p is true, then q must also be true.
In other words, if Siah is from Foya, then Foya must be in Lofa.
Source: WAEC / JAMB / NECO Classroom Archive (Record #69161)
Mathematics
WAEC / WASSCE 2023
Ratios, Proportions and Rates
Solution
m:n = \(2\frac{1}{3} : 1\frac{1}{5}\) and n : q = \(1\frac{1}{2} : 1\frac{1}{3}\), find q : m.
A
35 : 18
B
16 : 35
C
18 : 35
D
35 : 16
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
m:n = \(2\frac{1}{3} : 1\frac{1}{5}\) = m : n = \(\frac{7}{3} : \frac{6}{5}\)
\(\frac{7}{3} : \frac{6}{5}\) = \(\frac{7}{3} \div \frac{6}{5}\)
\(\frac{m}{n}\) = \(\frac{7}{3} \times \frac{5}{6}\)
\(\frac{m}{n}\) = \(\frac{35}{18}\) = m = \(\frac{35n}{18}\)
n : q = \(1\frac{1}{2} : 1\frac{1}{3}\) = \(\frac{3}{2} : \frac{4}{3}\)
\(\frac{n}{q}\) = \(\frac{3}{2} \times\frac{3}{4}\)
\(\frac{n}{q}\) = \(\frac{9}{8}\) = q = \(\frac{8n}{9}\)
q : m = \(\frac{8n}{9}\) : \(\frac{35n}{18}\)
\(\frac{q}{m}\) = \(\frac{8n}{9} \div \frac{35n}{18}\)
\(\frac{q}{m}\) = \(\frac{8n}{9}\times\frac{18}{35n}\)
=\(\frac{q}{m} = \frac{16}{35}\) = q : m = 16 : 35
Source: WAEC / JAMB / NECO Classroom Archive (Record #69108)
Mathematics
WAEC / WASSCE 2023
Ratios, Proportions and Rates
Solution
a. A car travels a distance of 112 km at an average speed of 70 km/h. it then travels a further 60 km at an average speed of 50 km/h. Calculate, for the entire journey, the total time taken.
b. if \(\frac{x}{y}\) = 2 and \(\frac{y}{z}\) = 3, find the value of \(\frac{ x + y}{y + z }\)
medium Difficulty
Verified Correct Answer: Option
Step-by-Step Mathematical Solution
a. The total time taken for the entire journey is the sum of time taken for each journey.
But Average speed = \(\frac { total distance covered}{ time taken}\)
then Time taken = \(\frac { total distance covered}{ time taken}\)
for the first journey(t1), d = 112km and speed = 70km/hr
\(t_1 = \frac{112}{70} = \frac{8}{5}\)hrs
for the second journey(t2), distance = 60km and speed = 50km/hr
\(t_2 = \frac{60}{50} = \frac{6}{5}\)hrs
Therefore, Total time taken = \( t_1 + t_2 = \frac{8}{5} + \frac{6}{5}\) = 2.8hrs.
b. if \(\frac{x}{y}\) = 2 , then x = 2y and if \(\frac{y}{z}\) = 3 then z = \(\frac{y}{3}\),
substituting, the values of x and z into \(\frac{ x + y}{y + z }\)
= \(\frac{2y + y}{y + \frac{y}{3}} = 3y\div\frac{4y}{3} = 3y\times\frac{3}{4y} = \frac{9}{4}\)
Therefore, \(\frac{ x + y}{y + z } = \frac{9}{4}\)
Source: WAEC / JAMB / NECO Classroom Archive (Record #69192)
Mathematics
WAEC / WASSCE 2023
Variations
Solution
M varies jointly as the square of n and square root of q. If M = 24 when n = 2 and q = 4, find M when n = 5, q = 9.
A
288
B
400
C
300
D
225
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
\(M ∝ n^2\sqrt{q}\)
\(M = Kn^2\sqrt{q}\)
K = \(\frac{M}{n^2\sqrt{q}}\)
K = \(\frac{24}{2^2\sqrt4}\)
k = \(\frac{24}{8} = 3\)
Now, let's find M when n = 5 and q = 9
M = \(Kn^2\sqrt{q}\)
M = \( 3\times5^2\sqrt9\)
\(M = 3\times25\times3\)
Therefore, M = 225.
Source: WAEC / JAMB / NECO Classroom Archive (Record #69178)