Question

The list price of a mobile is Rs. 4000. A customer gets two successive discounts, the first being 10%. Calculate, in percentage, the second discount, if the customer pays Rs. 3060 for it.

Answer 1

M.P. = Rs.4000, S.P. = Rs.3060
S.P. = `(1 - "d"_1/100)(1 - "d"_2/100)` of M.P.

⇒ 3060 = `(1 - 10/100)(1 - "d"_2/100) xx 4000`

⇒ 3060 = `(90)/(100) xx (1 - "d"_2/100) xx 4000` 

⇒ 3060 = `(1 - "d"_2/100) xx (90)/(100) xx 4000`

⇒ 3060 = `((100 - "d"_2)/100) xx 3600`

⇒ 100 - d₂ = `(3060 xx 100)/(3600)`
⇒ 100 - d₂ = 85
⇒ d₂ = 100 - 85
⇒ d₂ = 15%
Hence, the second discount is 15%.