A man invests ₹ 1550 in two parts, one part at the rate of 8 % interest and…
2024
A man invests ₹ 1550 in two parts, one part at the rate of 8 % interest and another part at the rate of 6 %. If the total interest earned in one year is ₹ 106, find the amount invested at each rate of interest, respectively.
Answer: A. ₹ 650 and ₹ 900 — Concept: For a one-year deposit, simple interest is I = P × R / 100, where P is the principal and R is the annual rate in percent. When a single sum is split…
- A.
₹ 650 and ₹ 900
- B.
₹ 700 and ₹ 850
- C.
₹ 750 and ₹ 800
- D.
₹ 800 and ₹ 750
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Show answer & explanation
Correct answer: A
Concept: For a one-year deposit, simple interest is I = P × R / 100, where P is the principal and R is the annual rate in percent. When a single sum is split into two parts placed at different rates, two conditions hold together: the two parts add back to the original sum, and the total interest is the sum of the interest earned by each part separately. Naming one part x turns those two conditions into a single linear equation in one unknown.
Application:
Let ₹x be the part invested at 8% per annum.
The remaining part, invested at 6% per annum, is then ₹(1550 − x).
Interest from the first part in one year = x × 8/100 = 0.08x.
Interest from the second part in one year = (1550 − x) × 6/100 = 93 − 0.06x.
The total interest for the year is ₹106, so 0.08x + 93 − 0.06x = 106.
Combining like terms gives 0.02x = 13, hence x = 13 ÷ 0.02 = 650.
Substituting back, the remaining part is ₹1550 − ₹650 = ₹900.
Cross-check: ₹650 at 8% earns 650 × 8/100 = ₹52 and ₹900 at 6% earns 900 × 6/100 = ₹54; these add to ₹106, and the parts themselves add to ₹1550, so both given conditions are satisfied. Working out every offered split makes the difference explicit:
Split (at 8%, at 6%) | Interest at 8% | Interest at 6% | Total for one year |
|---|---|---|---|
₹650, ₹900 | ₹52 | ₹54 | ₹106 |
₹700, ₹850 | ₹56 | ₹51 | ₹107 |
₹750, ₹800 | ₹60 | ₹48 | ₹108 |
₹800, ₹750 | ₹64 | ₹45 | ₹109 |
Because the amounts are asked in the order in which the rates are quoted — the 8% part first and the 6% part second — the required amounts are ₹650 and ₹900.