Question
A certain sum of money becomes 5 times of itself in 20
years at simple interest. In how many years does it become double of itself at the same rate of simple interest?Solution
Let the principal = Rs. x, Amount = Rs. 5x, Time = 20 years ∴ Simple Interest = Rs. (5x – x) = Rs. 4x Rate = [(4x × 100)/(x × 20)]% p.a. = 20% p.a. Now, Principal = Rs. x, Amount = Rs.2x, Rate = 20%p.a. Simple Interest = Rs. (2x − x)= Rs. x ∴  Time = (x × 100)/(x × 20) = 5 years.
152    142    122   ?     52    2
21, 37, 73, 137, ?, 381
What will come in place of the question mark (?) in the following series?
12, 13, 27, ?, 329, 1646
What will come in place of the question mark (?) in the following series?
325, 292, 262, 229, ?, 166
4, 4, 12, 60, ?, 3780
2807, 1400, 697, 346, 171, 84, 41, ?
254, ?, 1022, 1150, 1214, 1246
143 Â Â Â Â 119Â Â Â Â 107Â Â Â Â 101Â Â Â Â Â 98Â Â Â Â ?
204, 401, 640, ?, 1105, 1406
What will come in place of the question mark (?) in the following series?
60, 94, 184, 464, 1388, ?