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JAMB Mathematics Past Questions & Answers - Page 33

161.

A surveyor walks 500m up a hill which slopes at an angle of 30o. Calculate the vertical height through which he rises

A.

252m

B.

500m

C.

250m

D.

255m

Correct answer is C

h500 = sin 30o 

= 500 sin 30o 

= 500 x 12 

= 250m 

162.

The mean age group of some students is 15years. When the age of a teacher, 45 years old, is added to the ages of the students, the mean of their ages become 18 years. Find the number of students in the group. 

A.

7

B.

9

C.

15

D.

42

Correct answer is B

x xN

15 = xN

x = 15N........(i)

y = yNy=x+45N+1

181=15N+45N+1 

18(N + 1) = 15N + 45

18N + 18 = 15N + 45

18N - 15N = 45 - 18 

3N = 27 

N = 273 

= 9

163.

The sum of the interior angle of pentagon is 6x + 6y. Find y in terms of x.

A.

y = 6 - x

B.

y = 90 - x

C.

y = 120 - x

D.

y = 150 - x

Correct answer is B

Sum of interior angles = (2n - 4) 90o 

For perntagon, n = 5 

Sum of interior angles = 6 x 90o = 540o 

6x + 6y = 540o 

6(x + y) = 540o 

x + y = 540o6 = 90o 

y = 90o 

y = 90 - x

165.

Three consecutive terms of a geometric progression are give as n - 2, n and n + 3. Find the common ratio 

A.

32

B.

23

C.

12

D.

14

Correct answer is A

hn2=n+3n

n2 = (n + 3) (n - 2) 

n2 = n2 + n - 6

n2 + n - 6 - n2 = 0

n - 6 = 0

n = 6

Common ratio: nn2=662=64 = 32