Answer:
He must invest $ 2500 at 5% interest.
Explanation:
Given,
$ 5,000 is invested at 3% interest,
So, the profit after one year on $ 5000 = 3% of 5000
= 0.03 × 5000
= $ 150
Now, let x be the amount invested at 5%,
So, the profit after one year on x dollars = 5 % of x
= 0.05x
Thus, the total profit in both investment,
P = 150 + 0.05x
According to the question,
P = $ 275
⇒ 150 + 0.05x = 275
⇒ 0.05x = 125 ( subtracting 150 on both sides )
⇒ x = 2500 ( Dividing both sides by 0.05 )
Hence, he must invest $ 2,500 at 5% interest.