Question

Thomas takes 7 days to paint a house completely whereas raj would require 9 days to paint the same house completely. how many days will take to paint the house if both them work together.(give answers to the nearest integer)?

Answer 1

Hello,

Answer: 4 days

Solution:

As Thomos takes 7 days to paint a house.

Thus thomos one day work = 1/7 th part

Raj complete that work in 9 days

one day work of raj is = 1/9 th part

both 1st day work = 1/7 + 1/9 = (9+7)/63

= 16/63

Thomos and Raj's one one day work is 16/63

So they complete the entire work in 63/16 days

= 3.9375 days

On rounded to nearest interger  ≈ 4 days

So, they both take 4 days to paint the house completely.

Hope it helps you.

Answer 2

Thomas takes to paint a house completely = 7 days
so, thomas can do 1/7 part of work in 1 day.
Raj takes to paint the same house completely = 9 days
so,Raj can do 1/9 part of work in 1 day .

if both are working together then, in 1 days (1/7 + 1/9) = 16/63 part of work completed
e.g., both can do 16/63 part of work in a day
so, 63/16 days are required to do work completely .
hence, 63/16 days are required to paint a house completely.


method 2 :- Let A is number of days required to paint a house by Thomas and B is the number of days required to paint the same house by Raj.
use formula if both are working together ,
Number of days = AB/(A + B)

Here , A = 7 days and B = 9 days
so, number of days = 7 × 9/(7 + 9) = 63/16 days