Question

Benny received 4 pennies on thefirst day of the month, and eachday after that, he receivedquadruple the number ofpennies that he received theday before. On what day of themonth did Benny first receiveover 1 million dollars on a singleday?

Answer 1

0.04

4, 4^2, 4^3

4, 16,64,256

a = First term = 4

r= common ratio = 4

tn = a (r)^n-1

a = 4

r= 4

1000000= 4 (4)^n-1

250,000 = 4^n-1

log 250000 = log 4^n-1

5.39794 = n-1 log4

5.39794 = n-1 (0.6)

5.39794 / 0.6 = n-1

8.9 +1 = n

n = 10