A copper wire is bent in the shape of a square of area 81 cm². If the same wire is bent in the form of a semicircle, the radius (in cm) of the semicircle is 

• 16

• 14

• 10

• 7

122.

The volume (in m³) of rain water that can be collected from 1.5 hect of ground in a rainfall of 5 cm is

• 75

• 750

• 7500

• 75000

A can contain a mixture of two liquids A and B in the ratio 7 : 5. When 9 L of mixture are drawn off and the can is filled with B, the ratio of A and B becomes 7 : 9. Litres of liquid A contained by the can initially was

• 10

• 20

• 21

• 25

What number should be added to or subtracted from each term of the ratio 17 : 24 so that it becomes equal to 1 : 2?

• 5 is subtracted

• 10 is added

• 7 is added

• 10 is subtracted

The ratio of weekly incomes of A and B is 9 : 7 and the ratio of their expenditures is 4 : 3. If each saves ₹ 200 per week, then the sum of their weekly income is

• ₹ 3200

• ₹ 4200

• ₹ 4800

• ₹ 5600

Among three numbers, the first is twice the second and thrice the third. If the average of the three numbers is 49.5, then the difference between the first and the third number is

• 54

• 28

• 39.5

• 41.5

The mean of 50 numbers is 30. Later it was discovered that two entries were wrongly entered as 82 and 13 instead of 28 and 31. Find the correct mean.

• 36.12

• 30.66

• 29.28

• 38.21

A bicycle wheel makes 5000 revolutions in moving 11 km. Then, the radius of the wheel (in cm) is 

• 70

• 35

• 17.5

• 140

The perimeter of a triangle is 40 cm and its area is 60 cm². If the largest side measures 17 cm, then the length (in cm) of the smallest side of the triangle is

• 4

• 6

• 8

• 15

A shopkeeper allows a discount of 10% to his customers and still gains 20%. Find the marked price of the article which costs ₹ 450.

• ₹ 600

• ₹ 540

• ₹ 660

• ₹ 580