Question

1/4 of a rod was painted red. 2/5 was painted orange and 2/7 of the remainder was painted yellow. The yellow section was 20cm long how long was the rod

Answer 1

Answer: 200cm long

Step-by-step explanation:

Let the length of the rod be x

red = 1/4 of the rod , which means 1/4 of x

orange = 2/5 of x

The remainder = x - ($\frac{x}{4}$ +$\frac{2x}{5}$)

= x - ($\frac{13x}{20}$)

= $\frac{7x}{20}$

yellow = 2/7 of the remainder , that is

yellow = 2/7 of $\frac{7x}{20}$

yellow = $\frac{x}{10}$

and it was given that the yellow section was 20cm long , that is

$\frac{x}{10}$ = 20cm

x = 20 x10

x = 200

Therefore the rod was 200cm long