Wednesday, 17 November 2021

Sangster's virtual math class, Nov 17

 Simple interest calculations

 

Calculate how much interest you will earn if $5000 is in the saving account for a year. The interest rate is 2% per year

 

Step 1: convert interest rate from % to decimal (divide % by 100)

2¸ 100 = 0.02 (interest rate)

 

Step 2: multiply amount by interest rate by your deposit to determine how much interest is earned after a year

5000 (saving) x 0.02 (interest rate) = $100 (interest you earn after putting the money in a saving account for one year)

 

Step 3: add the principal (the initial amount) with the interest earned to get the total

- add the initial saving and the earned interest together

5000 + 100 = $5100 (in the saving account after one year)

 

 

Example 2: $550, interest rate is at 1.5%

 

Step 1: convert interest rate from % to decimal (divide % by 100)

1.5 ¸ 100 = 0.015

 

Step 2: multiply amount by interest rate by your deposit to determine how much interest is earned after a year

550 x 0.015 = 8.25

 

Step 3: add earned interest with saving (principal)

550 + 8.25 = 558.25

Summary: Interest rate is very low, and we earn close to nothing from our saving accounts. Therefore, we need to find other ways to grow our money.


Activity 2: Calculate how much interest will be earned every year for the following cases

a. $1000 at 1% per year                                  b. $1234 at 1% per year

¸ 100 = 0.01                                                 1 ¸ 100 = 0.01

1000 x 0.01 = 10                                             1234 x 0.01 = 12.34

1000 + 10 = 1010                                            1234 + 12.34 = 1246.34

 

 

c. $1000 at 5.5% per year                               d. $3210 at 5.75% per year

5.5 ¸ 100 = 0.055                                            5.75¸ 100 = 0.0575

1000 x 0.055 = 55                                           3210 x 0.0575 = 184.57

1000 + 55 = 1055                                            3210 + 184.57 = 3394.57

 

 

 

e. $1000 at 7.5% per year                               f. $1660 at 18.88% per year

7.5 ¸ 100 = 0.075                                            18.88¸ 100 = 0.1888

1000 x 0.075 = 75                                           1660 x 0.1888 = 313.41

1000 + 75 = 1075                                            1660 + 313.41 = 1973.41

 

 

 

 

g. $2500 at 18.88% for five years                   h. $3000 at 19.75% for four years

18.88 ¸ 100 = 0.1888

2500 x 0.1888 = 472 (interest for 5 years)

472 ¸ 5 =94.40 (interest earned in one year)                                    

2500 + 94.40 = 2594.40 (in bank account after one year)

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