Question 1
Number BasesWhat is the decimal equivalent of 134five
- A.36
- B.44
- C.105
- D.11
Show the answer and explanation
Answer: B (44)
1 × 25 + 3 × 5 + 4 = 44.
20 questions. Try each one, then open the answer to check yourself and read the explanation.
What is the decimal equivalent of 134five
Answer: B (44)
1 × 25 + 3 × 5 + 4 = 44.
3245six = Xnine, find x
Answer: C (1011)
3245₆ = 3 × 216 + 2 × 36 + 4 × 6 + 5 = 739; dividing by 9 repeatedly gives remainders 1, 1, 0, 1, so 739 = 1011₉.
Arrange in ascending order of magnitude: 5/9, 7/15, 11/20, 3/8
Answer: D (3/8, 7/15, 11/20, 5/9)
As decimals: 3/8 = 0.375, 7/15 ≈ 0.467, 11/20 = 0.55, 5/9 ≈ 0.556.
In a certain gathering, the ratio of men to women is 2:5. If there are 40 women, how many men are there?
Answer: A (16)
Men/40 = 2/5, so there are 16 men.
Testimony, Joy and Opeyemi share 60 notebooks in the ratio 2:4:6. How many notebooks does Opeyemi get?
Answer: C (30)
Opeyemi gets 6/12 of 60 = 30.
Evaluate 7√3 − √75
Answer: B (2√3)
√75 = 5√3, so 7√3 − 5√3 = 2√3.
5x+1 = 625, find x
Answer: C (3)
625 = 5⁴, so x + 1 = 4 and x = 3.
25x − 5x − 20 = 0, find x
Answer: A (1)
Let p = 5ˣ: p² − p − 20 = (p − 5)(p + 4) = 0. Since 5ˣ > 0, p = 5 and x = 1.
The simple interest on a certain sum of money invested for 4 years at 6.5% per annum is ₦416. Find the amount invested.
Answer: B (₦1600)
P = 100 × 416/(6.5 × 4) = 41,600/26 = ₦1,600.
If U = {1, 2, 4, 6, 9, 12}, A = {4, 6, 12}, B = {2, 4, 9}. Find A' ∩ B
Answer: C ({2, 9})
A' = {1, 2, 9}; the elements also in B are {2, 9}.
(2x − 1)/3 − (3x − 1)/4 = 1, find x
Answer: A (−13)
Multiply by 12: 4(2x − 1) − 3(3x − 1) = 12, so −x − 1 = 12 and x = −13.
The sum of three consecutive numbers is 36. Find the numbers
Answer: D (11, 12 and 13)
y + (y + 1) + (y + 2) = 36 gives y = 11: 11, 12, 13.
A man is four times as old as his son. In four years time, he will be three times as old. What are their present ages?
Answer: A (32 and 8)
4x + 4 = 3(x + 4) gives x = 8: the son is 8 and the man 32.
Factorize 16x2 − 9y2
Answer: C ((4x + 3y)(4x − 3y))
Difference of two squares: (4x)² − (3y)² = (4x + 3y)(4x − 3y).
What must be added to x2 − 22x to make it a perfect square?
Answer: B (121)
Add the square of half the coefficient of x: (22/2)² = 121.
The 8th term of a G.P is 640. If the first term is 5, find the common ratio.
Answer: B (2)
5r⁷ = 640, so r⁷ = 128 = 2⁷ and r = 2.
How many terms has the A.P whose first term is 15 and the last term is 57 given that the common difference is 3?
Answer: A (15)
57 = 15 + 3(n − 1), so n − 1 = 14 and n = 15.
Cos m = sin(m + 22°), find m.
Answer: B (34)
cos m = sin(90° − m), so m + 22 = 90 − m and m = 34°.
One angle of an octagon is 65°. The others are equal to each other. Find the value of each.
Answer: C (145°)
Interior angles of an octagon add to 6 × 180° = 1080°; (1080 − 65) ÷ 7 = 145°.
Evaluate log432 + log42
Answer: C (3)
log₄32 + log₄2 = log₄64 = 3.