Pranalee was practising for a 100 m running race. She ran 100 m distance 20 times. The time required, in seconds, for each attempt was as follows.

18 , 17 , 17 , 16 , 15 , 16 , 15 , 14 , 16 , 15 ,15 , 17 , 15 , 16, 15 , 17 , 16 , 15 , 14 , 15 Find the mean of the times taken for running.

Questions and their alternative answers are given. Choose the correct alternative answer.

Find the circumference of a circle whose area is 1386 cm².

Questions and their alternative answers are given. Choose the correct alternative answer.

The side of a cube is 4 m. If it is doubled, how many times will be the volume of the new cube, as compared with the original cube?

∆DEF and ∆LMN are congruent in the correspondence EDF ↔ LMN. Write the pairs of congruent sides and congruent angles in the correspondence.

The cost of a machine is ₹ 2,50,000. It depreciates at the rate of 4% per annum. Find the cost of the machine after three years.