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Business Math 03 - Calculating Interest Per Day (Practice 1)

This Math quiz is called 'Business Math 03 - Calculating Interest Per Day (Practice 1)' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to 14.

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You have learned how to calculate simple interest per year. It is pretty straightforward in that, using the formula, it is the principal times the interest rate times the number of years (I = PRT). But what happens if the principal amount is paid off in days rather than years? Let’s look at an example problem.

1.
\$8,300.00 at 9.25% for 212 days.
\$454.39
\$445.93
\$445.39
\$544.93
Working the problem
\$8,300.00 at 9.25% for 212 days.
I = PRT
8,300 x 0.0925 x 212/365
8,300 x 0.0925 = 767.75
\$767.75 per year
767.75 ÷ 365 (days) = 2.1034247 per diem
\$2.1034247 x 212 (days) = \$445.93
I = \$445.93
2.
\$2,500.00 at 4.25% for 300 days.
\$106.33
\$106.26
\$78.33
\$87.33
Working the problem
\$2,500.00 at 4.25% for 300 days.
I = PRT
2,500 x 0.0425 x 300/365
2,500 x 0.0425 = 106.25
\$106.25 per year
106.25 ÷ 365 (days) = 0.2910959 per diem
\$0.2910959 x 300 (days) = \$87.33
I = \$87.33
3.
\$425.00 at 2.85% for 90 days.
\$2.79
\$2.97
\$2.89
\$2.99
Working the problem
\$425.00 at 2.85% for 90 days.
I = PRT
425 x 0.0285 x 90/365
425 x 0.0285 = 12.11
\$12.11 per year
12.11 ÷ 365 (days) = 0.0331849 per diem
\$0.0331849 x 90 (days) = \$2.99
I = \$2.99
4.
\$1,525.00 at 4.85% for 309 days.
\$66.12
\$61.62
\$62.61
\$61.26
Working the problem
\$1,525.00 at 4.85% for 309 days.
I = PRT
1,525 x 0.0585 x 309/365
1,525 x 0.0485 = 73.96
\$73.96 per year
73.96 ÷ 365 (days) = 0.2026301 per diem
\$0.2026301 x 309 (days) = \$62.61
I = \$62.61
5.
\$64,725.00 at 8% for 180 days.
\$2,553.35
\$2,355.35
\$2,553,53
\$2,535.53
Working the problem
\$64,725.00 at 8% for 180 days.
I = PRT
64,725 x 0.08 x 180/365
64,725 x 0.08 = 5,178
\$5,178.00 per year
5,178 ÷ 365 (days) = 14.1863014 per diem
\$14.1863014 x 180 (days) = \$2,553.53
I = \$2,553.53
6.
\$18,515.00 at 5.175% for 265 days.
\$659.46
\$695.64
\$665.94
\$645.59
Working the problem
\$18,515.00 at 5.175% for 265 days.
I = PRT
18,515 x 0.05175 x 265/365
18,515 x 0.05175 = 958.15
\$958.15 per year
958.15 ÷ 365 (days) = 2.6250685 per diem
\$2.6250685 x 265 (days) = \$695.64
I = \$695.64
7.
\$25,000.00 at 6.75% for 243 days.
\$1,123.46
\$1,132.46
\$1,132.64
\$1,123.64
Working the problem
\$25,000.00 at 6.75% for 243 days.
I = PRT
25,000 x 0.0675 x 243/365
25,000 x 0.0675 = 1,687.50
\$1,687.50 per year
1,687.50 ÷ 365 (days) = 4.6232877 per diem
\$4.6232877 x 243 (days) = \$1,123.46
I = \$1,123.46
8.
\$675.00 at 5.2% for 332 days.
\$39.31
\$31.93
\$13.39
\$33.91
Working the problem
\$675.00 at 5.2% for 332 days.
I = PRT
675 x 0.052 x 332/365
675 x 0.052 = 35.10
\$35.10 per year
35.10 ÷ 365 (days) = 0.0961644 per diem
\$0.0961644 x 332 (days) = \$31.93
I = \$31.93
9.
\$3,750.00 at 7.13% for 118 days.
\$86.44
\$96.44
\$76.44
\$106.44
Working the problem
\$3,750.00 at 7.13% for 118 days.
I = PRT
3,750 x 0.0713 x 118/365
3,750 x 0.0713 = 267.38
\$267.38 per year
267.38 ÷ 365 (days) = 0.7325479 per diem
\$0.7325479 x 118 (days) = \$86.44
I = \$86.44
10.
\$100.00 at 3.23% for 60 days.
\$0.53
\$5.30
\$5.03
\$0.35
Working the problem
\$100.00 at 3.23% for 60 days.
I = PRT
100 x 0.0323 x 60/365
100 x 0.0323 = 3.23
\$3.23 per year
3.23 ÷ 365 (days) = 0.0088493 per diem
\$0.0088493 x 60 (days) = \$0.53
I = \$0.53