A principal of 560000 was deposited for 3years at compound interest if the interest earned was 120000 find correct to 3 significant figures the interest rate per annum?

To find the interest rate per annum, we can use the formula for compound interest:

A = P(1 + r/n)^(nt)

Where:
A = the amount after t years
P = the principal amount (560000)
r = the interest rate per annum
n = the number of times interest is compounded per year (assuming it is compounded annually, n = 1)
t = the number of years (3 years)
120000 = 560000(1 + r/1)^(1*3)

Simplify the equation:

120000 = 560000(1 + r)^3

Divide both sides by 560000:

0.214285714 = (1 + r)^3

Take the cube root of both sides:

1 + r = 0.606

Subtract 1 from both sides:

r = 0.606 - 1
r = -0.394

Convert the interest rate to a percentage:

r = -0.394 * 100
r = -39.4%

Therefore, the interest rate per annum is approximately -39.4%.

Step 1: Calculate the interest accrued

Interest accrued = Principal × Interest rate × Time

120000 = 560000 × Interest rate × 3

Step 2: Solve for the interest rate

Interest rate = 120000 / (560000 × 3)
Interest rate = 120000 / 1680000
Interest rate = 0.07142857

Step 3: Round to 3 significant figures

Interest rate = 0.0714

Therefore, the correct interest rate per annum to 3 significant figures is 0.0714 or 7.14%.