Question

$5,000 is invested in two different accounts yielding 3% and 3.5% interest. The interest earned on the two accounts is $155. How much money was invested at 3% interest?

Answer 1

$4000 was invested at 3% interest.

Solution:

Assume that x and y represent the amount at 3.5% and 3% respectively. So, according to the given statements we get two equations,

$x+y=5000\rightarrow(1)\\\\3x+3.5y=15500\rightarrow(2)$

On multiplying equation (1) by 30 and equation (2) by 10 we get,

$30 x+30 y=150000\\\\30 x+35 y=155000$

On solving both the equations we get,

$\Rightarrow5y=5000\rightarrow y=\frac{5000}{5}\rightarrow y=1000\rightarrow(3)$

On substituting (3) in (1) we get,

$\Rightarrow x+1000=5000\rightarrow x=5000-1000\rightarrow x=4000$

Therefore, $4000 was invested at 3% interest and $1000 was invested at 3.5% interest.