Susan saved $5000 per year in her retirement account for 10 years (during age 25-35) and then quit saving. However, she did not make any withdrawal until she turned 65 (i. e., 30 years after she stopped saving). Her twin sister, Jane did not save anything during the 1st 10 years (during age 25-30) but saved $5,000 per year for 30 years (during age 35-65). What will be the difference in their retirement account balance at age 65, if their investments earned an average return of 8.5% during the entire period

Instructions are below.

Explanation:

Giving the following information:

Susan:

Annual deposit = $5,000 for 10 years

Lumo-sum for 30 years

Interest rate = 8.5%

Jane:

Annual deposit = $5,000 for 30 years.

First, we will calculate the future value of Susan:

First 10 years:

FV = {A*[ (1+i) ^n-1]}/i

A = annual deposit

FV = {5,000*[ (1.085^10) - 1]}/0.085

FV = $74,175.50

Last 30 years:

FV = PV * (1+i) ^n

FV = 74,175.50 * (1.085^30)

FV = $857,050.14

Jane:

FV = {A*[ (1+i) ^n-1]}/i

A = annual deposit

FV = {5,000*[ (1.085^30) - 1]}/0.085

FV = $621,073.63

Earnings difference = 857,050.14 - 621,073.63 = $235,976.51 in favor of Susan.