Question

A) i) Calculate the simple interest earned if a deposit of $ 900,000 is left for 12 years at an interest rate of 3% .

ii) Calculate the interest rate for a 12 years investment of $600,000 to gained $180,000 interest.

Solve the following pairs of simultaneous equations 3x + y = 7 and 2x - 2y = 2

Answer 1

a)$ 324,000

ii) 2.5%

x=2, y=1

Explanation:

(a)Simple interest is calculated by the formula

`I=Prt`

I= Interest received

P=Principal

r= interest rate (per year)

t=time (in years)

I= ($900,000)(12)(3%)

I=$324,000

(ii)From the formula above, we find r

`I=Prt\\\\r=(I)/(Pt)\\ \\r=((180,000))/((600,000)(12))\\\\\\r=0.025\\\\`

r=2.5%

_______________________________

3x+y=7

2x-2y=2

Let's take 2x-2y=2

we divide by 2 both sides and we get

x-y = 1

so x = 1+y

and replace it in the other formula:

3(1+y) + y = 7

3+3y+y = 7

3 + 4y = 7

4y = 7-3

4y= 4

y = 1

x = 1+y

x = 1+1

x = 2