Question

(a) In a G.P of 6 terms the first and last terms are 5 and 160, find the remaining terms.

(b) Ganga marked a dot in the first square, 2 dots in the second, 4 in the third square and so on. How many dots should she mark in the 8^th square?

(c) Sahil purchased certain number of laddus and distributed five of his friends. He gave half of them to the first friend, half of the remaining to the second and so on. He and his fifth friend are remaining 33 laddus. How many laddus did Sahil purchase?

Answer 1

(a)In the G.P. of 6 terms, the first and last terms are respectively given as 5 and 160.

∴

Hence, the G.P is 5, 10, 20, 40, 80, 160.

(b) It is clear that the numbers 1, 2, 4 … form a G.P. We need to find its 8^th term.

Here, and .

Thus, she marked 128 dots in the 8^th square.

(c) The original number of laddus purchased and the numbers of laddus left after giving them to each friend form a G.P., where the common ratio is and the last term (5^th term) is 33.

Hence, Sahil purchased 528 laddus.