The marked price of a watch was Rs. 720. A man bought the

The marked price of a watch was Rs. 720. A man bought the same for Rs. 550.80 after getting two successive discounts, the first being 10%. The second discount rate is

Marked price = Rs. 720
Discount = 10%
∴ After a discount of 10%,

S.P. = Rs.		720 × 90
		100

= Rs. 648
Final S.P. = Rs. 550.80
∴ Discount = Rs. (648 – 550.80) = Rs. 97.2
If the second discount be x%, then

648 × x	= 97.2
100

⇒ x =	97.2 × 100	= 15%
	648

Second method :
S.P. = Rs. 550.80, M.P. = Rs. 720
D₁ = 10%, D₂ = ?

S.P. = M.P.		100 − D₁			100 − D₂
		100			100

550.80 = 720		100 − 10			100 − D₂
		100			100

550.80 × 100 × 100	= 100 − D₂
720 × 90

85 = 100 − D₂
D₂ = 100 − 85
D₂ = 15%