RRB RPF RPSF SI and CONS Model Papers 3 with solutions

Question : 30 of 120

Marks: +1, -0

A man ordered 4 pairs of black socks and some pairs of brown socks. The price of a black socks is double that of a brown pair. While preparing the bill the clerk interchanged the number of black and brown pairs by mistake which increased the bill by 50%. The ratio of the number of black and brown pairs of socks in the original order was :

2 : 1
1 : 4
1 : 2
4 : 1

Validate

Solution:

(b) Number of brown socks = x
Price of brown socks = Rs. y per pair
Price of black socks = Rs. 2y per pair

∴ 4 y + x × 2 y = { 150 } /{ 100 } ( 4 ×2 y + x y )

⇒ 4 + 2 x = { 3 } /{ 2 } ( 8 + x )

⇒ 8 + 4 x = 24 + 3 x

⇒ x = 24 - 8 = 16

∴ Requried ratio

= 4 : 16 = 1 : 4

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