The figure, not drawn to scale, is made of two connected cubical tanks, M and N. Tank M is sealed at the top and completely filled to the brim. Tank N is ⁴₅ filled with 151660 mℓ of water. The height of the water level in Tank N is 5 cm higher than that in Tank M. Height of Tank N is 70 cm. Water is then drained from the container and the height of the water level from the base falls to 28 cm.

1. What is the capacity of Tank N in litres?
2. What is the volume of water in the tank now in litres?

(a)
⁴₅ of Tank N = 151660 mℓ
¹₅ of Tank N = 151660 ÷ 4 = 37915 mℓ
⁵₅ of Tank N = 37915 x 5 = 189575 mℓ

1 ℓ = 1000 mℓ

Capacity of Tank N = 189575 mℓ = 189.575 ℓ

(b)
Fraction of Tank N not filled
= 1 - ⁴₅
= ¹₅

Height of Tank N not filled
= ¹₅ x 70 cm
= 14 cm

Height of Tank M
= 70 - 14 - 5
= 51 cm

Volume of remaining water in Tank M
= 51 x 51 x 28
= 72828 cm³ 

Volume of remaining water in Tank N
= 70 x 70 x 28
= 137200 cm³ 

Total volume of remaining water in the tank
= 72828 + 137200
= 210028 cm³

1 ℓ = 1000 cm³
210028 cm³ = 210.028 ℓ

Answer(s): (a) 189.575 ℓ; (b) 210.028 ℓ