Multiple choice

The simple interest on a certain sum of money at 3$\displaystyle ^ \frac{1}{2}$% per annum for 2$\displaystyle ^ \frac{5}{21}$ years is Rs.658. The sum is

  1. $Rs.7,480$
  2. $Rs.7,840$
  3. $Rs.8,120$
  4. $Rs.8,400$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Rate = 3.5% = 7/2%. Time = 2 + 5/21 = 47/21 years. SI = (P * R * T) / 100. 658 = (P * 7/2 * 47/21) / 100. 658 = (P * 329 / 42) / 100. P = 658 * 4200 / 329 = 2 * 4200 = 8400.

AI explanation

Using the principal formula Principal = (Simple Interest x 100) / (Rate x Time), we convert the mixed fractions to improper fractions to get a rate of 7/2 percent and a time of 47/21 years. Substituting the values gives Principal = (658 x 100) / ((7/2) x (47/21)), which simplifies to Rs. 8,400.

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