Question

A shopkeeper bought three watches w1,w2 and w3 from a dealer and sold them to three different customers. The ratio of the selling prices of the watches w1,w2andw3 was 2:3:4 . The shopkeeper gains 30%and20% on the watches w1andw2 respectively but loses 40% on the watch w3 . What was the shopkeeper's 'approximate percent gain or loss in the whole transaction?

Answer 1

sp of W1=2X+30%

W2=3X+20%

W3=4X-40%

total SP= 2x+3x+4x=9x

cp of w1=100/130×2x = 20x/ 13

cp of w2= 100/120×3x = 30x/12

cp of w3 = 100/60×4x = 20x/3

( because = 100-40 = 60)

total cp= 20x/13+30x/12+20x/3

= 240x+390x+1040x/13×4×3

=1670x/156

=10.70x

loss = CP-SP

= 1070x-9x

= 1.70x

loss % = 1.70x/10.70x × 100

= 15.88%

= 16%