JAMB Mathematics Past Questions & Answers - Page 415

2,071.

x√2

2x²

x²

Correct answer is B

Hint: prepare a three-columned table, one for (x), another for the (deviation), and the last for the (squared-deviation).

Sum of (x) = 15x, algebraic sum of (deviation) = zero (0)
Sum of (squared-deviation) = 10x²

Variance = ∑(squared-deviation)/n = 10x²/5 = 2x²

2,072.

If U = {x : x is an integer and 1 \(\leq\) x \(\leq\) 20
E₁ = {x : x is a multiple of 3}
E₂ = {x : x is a multiple of 4}
and an integer is picked at random from U, find the probability that it is not in E₂

3/4

3/10

1/4

1/20

View answer & explanation

Correct answer is A

U = {1, 2, 3, 4, 5,..., 20}
E1 = {3, 6, 9, 12, 15, 18}
E2 = {4, 8, 12, 16, 20}
P(E1) = 5/20
P(not E1) = 1 - (5/20) = 15/20 = 3/4

2,073.

Given that the various faces of a fair dice 1, 2, 3, 4, 5, 6 appeared 30, 43, 54, 40, 41, 32 times respectively in a single toss. Picture the figures as being represented in a simple table with number (X) against frequency (f).

If a pie chart is used to depict the data, the angle corresponding to 4 is?

10°

16°

40°

60°

View answer & explanation

Correct answer is D

Angle corresponding to 4 is 40/240 x 360/1 = 60°

Note that total angle in a circle is 360°.
Note also that sum of the frequencies given is 240.

2,074.

In how many ways can the word MATHEMATICS be arranged?

11!/(9! 2!)

11!/(9! 2! 2!)

11!/(2! 2! 2!)

11!/(2! 2!)

View answer & explanation

Correct answer is C

Number of letter in MATHEMATICS = 11
Number of letter M = 2
Number of letter T = 2
Number of letter A = 2

Arrangement = 11!/(2! 2! 2!) ways

2,075.

If the mean of the numbers 0, (x+2), (3x+6), and (4x+8) is 4, find their mean deviation.

View answer & explanation

Correct answer is C

Mean = {0 + (x+2) + (3x+6) + (4x+8)}/4 = 4
=> 0 + (x+2) + (3x+6) + (4x+8) = 16
8x + 16 = 16
x = 0

Now prepare a table showing the deviation of each of 0, (x+2), (3x+6) and (4x+8), adding the deviations will give 12.

Thus M.D = 12/4 = 3