JAMB Mathematics Past Questions & Answers - Page 30

146.

Two numbers are removed at random from the numbers 1, 2, 3 and 4. What is the probability that the sum of the numbers removed is even?

A.

\(\frac{2}{3}\)

B.

\(\frac{1}{2}\)

C.

\(\frac{1}{3}\)

D.

\(\frac{1}{4}\)

Correct answer is B

\(\begin{array}{c|c} 1 & 2 & 3 & 4\\\hline 1(1, 1) & (1, 2) & (1, 3) & (1, 4)\\ \hline 2(2, 1) & (2 , 2) & (2, 3) & (2, 4) \\ \hline 3(3, 1) & (3, 2) & (3, 3) & (3, 4)\\ \hline 4(4, 1) & (4, 2) & (4, 3) & (4, 4)\end{array}\)

sample space = 16

sum of nos. removed are (2), 3, (4), 5

3, (4), 5, (6)

(4), 5, (6), 7

(5), 6, 7, (8)

Even nos. = 8 of them

Pr(even sum) = \(\frac{8}{16}\)

= \(\frac{1}{2}\)

147.

The mean of ten positive numbers is 16. When another number is added, the mean becomes 18. Find the eleventh number

A.

3

B.

16

C.

38

D.

30

Correct answer is C

Mean of 10 numbers = 16

The total sum of numbers = 16 x 10 = 160

Mean of 11 numbers = 18

Total sum of numbers = 11 x 18

= 198

The 11th no. = 198 - 160

= 38

148.

4, 16, 30, 20, 10, 14 and 26 are represented on a pie chart. Find the sum of the angles of the bisectors representing all numbers equals to or greater than 16

A.

48o

B.

84o

C.

92o

D.

276o

Correct answer is D

Given that 4, 16, 30, 20, 10, 14 and 26

Adding up = 120

nos \(\geq\) 16 are 16 + 30 + 20 + 26 = 92

The requires sum of angles = \(\frac{92}{120}\) x \(\frac{360^o}{1}\)

= 276o

149.

The locus of a point which moves so that it is equidistant from two intersecting straight lines is the?

A.

perpendicular bisector of the two lines

B.

angle bisector of the two lines

C.

bisector of the two lines

D.

line parallel to the two lines

Correct answer is B

The required locus is angle bisector of the two lines

150.

A cylinder pipe, made of metal is 3cm thick.If the internal radius of the pipe is 10cm.Find the volume of metal used in making 3m of the pipe.

A.

153\(\pi\)cm3

B.

207\(\pi\)cm3

C.

15 300\(\pi\)cm3

D.

20 700\(\pi\)cm3

Correct answer is D

Volume of a cylinder = πr\(^2\)h

First convert 3m to cm by multiplying by 100

Volume of External cylinder = \(π \times 13^2 \times 300\)

Volume of Internal cylinder = \(π \times 10^2 \times 300\)

Hence; Volume of External cylinder - Volume of Internal cylinder

Total volume (v) = \(π (169 - 100) \times 300\)

V = \(π \times 69 \times 300\)

V = 20700πcm\(^3\)