Question

. A certain sum doubles itself in 20 yrs. In how many years it will become 7 times
(a) 100
(b) 120
(c) 140
(d) none
with explanation ​

Answer 1

Answer:

(c) 120 yrs

Step-by-step explanation:

let x doubles to 2x in 20 yrs

= it becomes 7 times = x+6x=120 yrs required as x is initially given