Question

2. bob invests 100 dollars in a fund that yields 15% simple interest monthly. if bob invests the principal in the middle of january, which is the first month will he have more than $200 total?

Answer 1

Formula used :

$S.I = \frac{PRT}{100}\\A = P +S.I$

where P is the Principal

R is rate of interest per annum

T is time in years

A is amount

Given : P=$100 ; R=15% per month = 15% * 12 per year; Amount = $200

T=?

$SI = \frac{100* 15*12 *T}{100}$

Also,

$SI = A-P = 200-100=100$

so, we have

$100 = \frac{100* 15*12 *T}{100}\\\\ T = \frac{100}{15 *12}  years\\\\ T= \frac{100}{15*12} *12   months$

∴  T = 6.67 months ≈ 7 months

Given Bob invests the money in the mid of January. So, AUGUST will be the first month when the amount will be more than $200.