Question

A man buys 3 cows and
8 goats in 47,200. Instead if he would have bought 8 cows and 3 goats, he
had to pay 53,000 more. Cost of one cow is :

• A. 11,000
• B. 12,000
• C. 13,000
• D. 10,000

Answer 1

The correct option is B 12,000

let cost of each cow $=Rsx$

Cost of each cow $=Rsy$

Given, $3x+8y=\mathrm{47200...}\left(1\right)$

$\Rightarrow 8y=47200-3x$

$\Rightarrow y=\frac{47200-3x}{8}...\left(2\right)$

Also $8x+3y=47200+53000$

$\Rightarrow 8x+3y=100200$

$\Rightarrow 3y=100200-8x$

$\Rightarrow y=\frac{100200-8x}{3}...\left(3\right)$

from (2) & (3) $y=y$

$\Rightarrow \frac{47200-3x}{8}=\frac{100200-8x}{3}$

$\Rightarrow 141600-9x=801600-64x$

$\Rightarrow 55x=660000$

$\Rightarrow x=12,000$