Answer: 7 people need 16 minutes to paint 4 walls.
Step-by-step explanation:
Since we have given that it takes 63 minutes to paint 9 walls ,
So, we will apply "time and work formula" i.e.
[tex]\frac{M_1\times D_1\times H_1}{W_1}=\frac{M_2\times D_2\times H_2}{W_2}[/tex]
where,
H denotes number of hours or minutes,
D denotes number of days
M denotes number of men
W denotes work done them,
So, we need to calculate number of minutes for 7 people to paint 4 walls,
[tex]\frac{63\times 4}{9}=\frac{M\times 7}{4}\\\\7\times 4=\frac{M\times 7}{4}\\\\16=M[/tex]
So, 7 people need 16 minutes to paint 4 walls.
