JAMB Mathematics Past Questions & Answers - Page 378

1,886.

A box contains 5 blue balls, 3 red balls and 2 white balls. Two balls are selected from the box with replacement. Find the probability of obtaining two blue or two red balls

A.

17/50

B.

3/25

C.

1/50

D.

3/250

Correct answer is A

Blue balls = 5
Red balls = 3
White balls = 2
Total = 10
P(Two blue) = 5/10 * 5/10 = 25/100
P(Two Red) = 3/10 * 3/10 = 9/100
∴P(Two blue or two red balls)
= 25/100 + 9/100
= 34/100
= 17/50

1,887.

How many possible ways are there of seating seven people P,Q,R,S,T,U and V at a circular table

A.

360

B.

720

C.

2520

D.

5040

Correct answer is B

(n - 1)! = (7 - 1)!
= 6!
= 6*5*4*3*2*1
= 720 ways

1,888.

In how many ways can 6 coloured chalks be arranged if 2 are the same colour?

A.

60

B.

120

C.

240

D.

360

Correct answer is D

\(\frac{6!}{2!}=ways=\frac{6\times5\times4\times3\times2!}{2!}\\=6\times5\times4\times3\\=360\hspace{1mm}ways\)

1,889.

Find the value of t if the standard deviation of 2t, 3t, 4t, 5t, and 6t is √2

A.

1

B.

2

C.

3

D.

4

Correct answer is A

No explanation has been provided for this answer.

1,890.

The model height and range of heights 1.35, 1.25, 1.35, 1.40, 1.35, 1.50, 1.35, 1.50, and 1.20 are m and r respectively. Find m+2r.

A.

1.35

B.

1.65

C.

1.95

D.

3.00

Correct answer is C

1.35, 1.25, 1.35, 1.40, 1.35, 1.50, 1.35, 1.50, and 1.20
Modal height = 1.35
Range (r) = 1.50 - 1.20
= 0.30
∴m + 2r = 1.35 + 2(0.30)
= 1.35 + 0.60
= 1.95