When the price of egg was raised by \(N2\) an egg. the number of eggs which can be bought for \(\# 120\) is reduced by 5 . The present price of an egg is ____________
A. #6 B. #7 C. #8 D. #10
Correct Answer: C
Explanation
Let old/initial price of 1 egg \(=\# x\) Let no of eggs #120 would buy (at that time) be \(y_{1}\) l egg \(=\# x\) \(y_{1}=\# 120\) \(y_{1}=\# \frac{120}{x}\)rom the question. \(y_{1}-5=y_{2}\)rom the question. \begin{aligned} y_{1}-5 &=1 \\ \text { i.e. } \frac{120}{x}-5 &=\frac{120}{x+2} \\ \frac{120-5 x}{x} &=\frac{120}{x+2} \end{aligned} \begin{aligned} (120-5 x)(x+2) &=120 x \\ 120 x+240-5 x^{2}-10 x &=120 x \\ x-5 x^{2}-10 x+240 &=0 \end{aligned} divide all through by 5 \(x^{2}+2 x-48=0\) by factorizing \begin{aligned} &x^{2}+8 x-6 x-48=0 \\ &x(x+8)-6(x+8)=0 \\ &x-6=0 x+8=0 \\ &x=6 x=-8 \end{aligned} since the value of money cannot be negative. x=6 Therefore. \begin{aligned} \text { the new price/present price } &=+2 \\ &=\# 6+\# 2 \\ &=\# 8 \end{aligned}