21.

A telegraph post is bent at a point above the ground due to storm. Its top just touches the ground at a distance of 10√3 from its foot and makes an angle of 30° with the horizontal. Then height (in metres) of the telegraph post is

• 30

• 24

• 20

• 28

Three Science classes A, B and C take a Life Science test. The average score of class A is 83. The average score of class B is 76. The average score of class C is 85. The average score of class A and B is 79 and C is 81. Then the average score of classes A, B and C is

• 81.5

• 81

• 80.5

• 80

A sum of money placed at compound interest doubles itself in 5 years. It will amount to eight times of itself at the same rate of interest in

• 20 years

• 10 years

• 12 years

• 15 years

A and B can do a given piece of work in 8 days, B and C can do the same work in 12 days and A, B, C complete it in 6 days. Number of days required to finish the work by A and C is

• 16

• 8

• 12

• 24

A sum of money is paid back in two annual instalments of Rs. 17,640 each, allowing 5% compound interest compounded annually. The sum borrowed was

• ₹ 32,800

• ₹ 32,200

• ₹ 32,000

• ₹ 32,400

If 90 men can do a certain job in 16 days, working 12 hours per day, then the part of that work which can be completed by 70 men in 24 days, working 8 hours per day is

• 1/3

• 2/3

• 7/9

• 5/8

A man purchases some oranges at the rate of 3 for Rs. 40 and the same quantity at 5 for Rs. 60. If he sells all the oranges at the rate of 3 for Rs. 50, find his gain or loss per cent (to the nearest integer).

• 32% profit

• 31% loss

• 34% loss

• 31% profit

Let x be the smallest number, which when added to 2000 makes the resulting number divisible by 12, 16, 18 and 21. The sum of the digits of x is

• 7

• 5

• 6

• 4

The value of 
cot 41°. cot 42°. cot 43°. cot 44°. cot 45°. cot 46°. cot 47°. cot 48°. cot 49°.

• 1

• 0

• 

• 

If O is the circumcentre of a triangle ABC lying inside the triangle, then ∠OBC + ∠BAC is equal to

• 90°

• 60°

• 110°

• 80°