The rate of interest per annum at which the total simple interest of a certain capital for 1 year is equal to the total simple interest of the same capital at the rate of 5% per annum for 2 years is :
Let the certain capital = P
and the required rate of interest = r%
According to question,
P×r×1/100 = P×5×2/100
∴ r = 5×2 = 10%
What should come in place of the question mark (?) in the following number series
4 6 12 ? 90 315 1260
12 12 18 36 90 270 ?
1015 508 255 129 66.5 ? 20.875
8 9 20 63 256 1285 ?
980 484 236 112 50 ? 3.5