Question

Find the single discount(in % and rounded off to next digit) equivalent to following successive discount $10\%,15\%,20\%$

Answer 1

Let the original price of item be Rs $x$.

First discounted price = $90\%$ of Rs $x$ = Rs $\frac{90}{100}x$

Second discounted price = $85\%$ of Rs $\frac{90}{100}x$ = Rs $\frac{85}{100}\frac{90}{100}x$

Final discounted price = $80\%$ of Rs $\frac{85}{100}\frac{90}{100}x$ = Rs $\frac{80}{100}\frac{85}{100}\frac{90}{100}x$ = Rs $\frac{612000}{1000000}x$ = Rs $\frac{61.2}{100}x$ = $61.2\%$ of Rs $x$.

Hence, the total equivalent discount = $(100-61.2)\%$ = $38.8\%\approx 39\%$