Math, asked by shauryasai371, 11 months ago

Ashish can paint his idol in 20 minutes and his sister Chinki can do so in 25 minutes.
They paint it together for five minutes. At this juncture they have a quarrel ,and Chinki
withdraws herself from painting. In how many minutes will Ashish finish the painting of
the remaining idol?​

Answers

Answered by ChitranjanMahajan
14

Ashish will finish the painting of the remaining idol in 11 minutes.

• Let the total idol be taken as 1.

• Given,

Time taken by Ashish to paint the entire idol alone = 20 minutes

=> Part of the idol painted by Ashish in 1 minute = 1 / 20

• Also given,

Time taken by Chinki to paint the entire idol alone = 25 minutes

Part of the idol painted by Chinki in 1 minute = 1 / 25

• Part of the idol painted by Ashish and Chinki together in 1 minute = ( 1 / 20) + ( 1 / 25 )

L.C.M. of 20 and 25 is 100.

∴  ( 1 / 20) + ( 1 / 25 ) = [ (1 × 5) + (1 × 4) ] / 100

= (5 + 4) / 100

= 9 / 100

• Part of the idol painted by Ashish and Chinki together in 5 minutes = ( 9 / 100 ) × 5

= ( 9 × 5 ) / 100

= 9 / 20

• Now, part of the idol still left to be painted = 1 - ( 9 / 20 )

= [ (1 × 20) - 9 ] / 20

= ( 20 - 9 ) / 20

= 11 / 20

• Since Chinki leaves after 5 minutes, 11 / 20 parts of the idol has to be painted by Ashish alone.

• As stated before, Ashish takes 20 minutes to paint the entire idol, therefore, he will take lesser time to paint 11 / 20 parts of the idol.

• Thus, time taken by Ashish to paint 11 / 20 parts of the idol = (11 / 20) × 20 minutes = 11 minutes (Answer)

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