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If ₹21 is the true discount on ₹371 for a certain time, what is the true discount on the same amount for double that time, the rate being the same in both the cases?
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- ₹39.00
- ₹35.75
- ₹40.00
- ₹39.75
- None of these
Correct Option: D
Here ,( Sum Due ) Amount = ₹ 371 , True discount = ₹ 21
₹21 is the interest on ₹( 371 - 21 ) = ₹350
Present worth = ₹350
| ∴ | Present worth × no of year × rate | = True Discount |
| 100 |
| ∴ | 350 × no of year × rate | = 21 |
| 100 |
| ⇒ Number of year × rate = | 2100 | = 6 |
| 350 |
∴ Twice number of years × rate ( R x T )= 12
Now, on ₹112, the True Discount is ₹12
| ∴ on ₹371, True Discount = ₹ | Amount × Rate × Time |
| 100 + ( Rate × Time ) |
| True Discount = ₹ | 12 | × 371 |
| 112 |
True Discount = ₹39.75
