Hello.
Time taken by 3 person to paint one wall=32÷4=8minstime taken by 1 person to paint one wall=8*3=24minstime taken by 1 person to paint 7 walls=24*7=168 minstime taken by 4 persons to paint 7 walls=168÷4=42mins
Answer= 42 minutes
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Mark is 20. 55 - 15 = 40, 40 / 2 = 20. Mark is 20
(32 + 90 + 92 + 82 + 64 + x) / 6 = 85
(360 + x) / 6 = 85
360 + x = 85 * 6
360 + x = 510
x = 510 - 360
x = 150 <===
Let,the time taken by larger pipe = x
By smaller pipe = x+5
It would be: 1/x + 1/(x+5) = 9/100
= x+5+x /(x)(x+5) = 9/100
= 2x+5 / x²+5x = 9/100
= 100(2x + 5) = 9(x² + 5x)
= 200x + 500 = 9x² + 45x
= 9x² - 155x - 500 = 0
= 9x² - 180x + 25x - 500 = 0
= 9x(x - 20) + 25(x - 20) = 0
= (9x + 25) (x - 20) = 0
= x = -25/9 or x = 20
Time can't be in negative so -25/9 is rejected.
Now,x + 5 = 20 + 5 = 25
In short, Your Larger pipe takes 20 minutes and smaller pipe takes 25 minutes
Hope this helps!
The answer I am not sure but will try
Ans: 110
