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A shopman bought pens at the rate of 7 for $ 10 and sold them at a profit of 40%. How many pens would a customer get for $ 10?
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- 6
- 4
- 5
- 3
Correct Option: C
Here , C.P. of 7 pens = $ 10
On profit 40% ,
| S.P. of 7 pens = | = $ 14 | 100 |
| ∴ S.P. of 1 pen = | = $ 2 | 7 |
Clearly, 5 pens were sold for $ 10
Second method to solve this question :
Here, a = 7, p = 10 and b = ?, q = 10, Gain% = 40%
| Gain % = |  | aq - bp |  | × 100% | |
| bp |
| 40 = | | 7 × 10 - b × 10 | | × 100% | ||
| b × 10 |
⇒ 4b = 70 – 10b
⇒ 14b = 70
| b = | b = 5 | 14 |
