Raghu bought some pens at the rate of 12 for Rs 100 and an equal number of pens at 15 for Rs 135.

Raghu bought some pens at the rate of 12 for Rs 100 and an equal number of pens at 15 for Rs 135. How many pens should he sell for Rs 260, so as to make a profit of 20%?

Options
a) 20
b) 30
c) 24
d) 25

Solution

As per question
Pen bought of 12 for Rs. 100 is = x
Cost of pen = $\frac {100}{12} \times x = \frac {25x}{3}$
Pen bought of 15 for Rs. 135 is also x
Cost of pen = $\frac {135}{15} \times x = \frac {27x}{3}$
Total cost = $\frac {25}{3}x + \frac {27}{3}x = \frac {52}{3}x$
Require profit = 20%
SP = 1.2 x CP
SP $1.2 \times \frac {52}{3}x$ = 20.8x
Selling price for pen = $\frac {20.8x}{2x}$ = 10.4
No. of pen sold is Rs. 260 = $\frac {260}{10.4}$ = 25