Answer:
Note: The complete question is attached below as picture
A = P(1+r/100)^n Where A is future value, P is present value, r is rate of interest and n is time period
1. A = P(1+r/100)^n
1042.51 = 480(1.09)^n
(1042.51/480) = 1.09^n
Taking log on both sides
log(1042.51/480) = n*log 1.09
n = log(1042.51/480)/log 1.09
n = 9 years.
2. A = P(1+r/100)^n
53.26 = 31(1.07)^n
(53.26/31) = 1.07^n
Taking log on both sides
log(53.26/31) = n*log 1.07
n = log(53.26/31)/log 1.07
n = 8 years
3. A = P(1+r/100)^n
383.59 = 100(1.13)^n
(383.59/100) = 1.13^n
Taking log on both sides
log(383.59/100) = n*log 1.13
n = log(383.59/100)/log 1.13
n = 11 years.
4. A = P(1+r/100)^n
66.91 = 53(1.06)^n
(66.91/53) = 1.06^n
Taking log on both sides
log(66.91/53) = n*log 1.06
n = log(66.91/53)/log 1.06
n = 0.10121516027 / 0.025306
n = 3.9997
n = 4 years.