Mrs wong wants to invest $50000 for 3 years.

Simple interest of 5% p.a. for the first year, and then interest compounded monthly at 3% p.a. in every subsequent year. Find the amount she will receive.

50000(1+5/100)[1+(3/12)/100]^(2*12)

To calculate the amount Mrs. Wong will receive after 3 years, we need to break down the investment into different periods and calculate the interest earned in each period separately.

First Year:
Mrs. Wong will earn simple interest of 5% per annum for the first year. The formula to calculate simple interest is:

Simple Interest = Principal x Rate x Time

Given:
Principal (P) = $50000
Rate (R) = 5% = 0.05 (in decimal form)
Time (T) = 1 year

Using the formula, we can calculate the simple interest for the first year:

Simple Interest = $50000 x 0.05 x 1 = $2500

After the first year, Mrs. Wong will have the original principal plus the interest earned, which amounts to:

Amount after 1 year = Principal + Simple Interest = $50000 + $2500 = $52500

Second Year:
From the second year onwards, the interest will be compounded monthly at a rate of 3% per annum. To calculate the compound interest, we can use the formula:

Compound Interest = Principal x (1 + Rate/n)^(n x Time)

Where:
Principal (P) = $52500 (amount after 1 year)
Rate (R) = 3% = 0.03 (in decimal form)
Time (T) = 1 year
Number of compounding periods (n) = 12 (monthly compounding)

Using the formula, we can calculate the compound interest for the second year:

Compound Interest = $52500 x (1 + 0.03/12)^(12 x 1) = $52500 x (1 + 0.0025)^12 = $53418.25

After the second year, Mrs. Wong will have the previous amount plus the interest earned, which amounts to:

Amount after 2 years = Amount after 1 year + Compound Interest = $52500 + $53418.25 = $105918.25

Third Year:
Using the same formula for compound interest, we can calculate the interest earned in the third year based on the amount calculated after 2 years:

Principal (P) = $105918.25 (amount after 2 years)
Rate (R) = 3% = 0.03 (in decimal form)
Time (T) = 1 year
Number of compounding periods (n) = 12 (monthly compounding)

Compound Interest = $105918.25 x (1 + 0.03/12)^(12 x 1) = $105918.25 x (1 + 0.0025)^12 = $108862.37

After the third year, Mrs. Wong will have the previous amount plus the interest earned, which amounts to:

Amount after 3 years = Amount after 2 years + Compound Interest = $105918.25 + $108862.37 = $214780.62

Therefore, Mrs. Wong will receive $214780.62 after 3 years.