The figure shows the amount of water in two rectangular tanks, M and N, at first. Lee poured ¹₅ of the water from M into N to fill it to the top, without overflowing.

1. How much water was there in Tank M at first?
2. Lee then poured all the water from Tank N into Tank M. 27632 cm³ of water overflowed from Tank M. What was the height of Tank M?

(a)
Volume of water to fill Tank N
= 22 x 19 x 21
= 8778 cm<sup>3

1</sup>₅ of volume of water in Tank M at first = 8778 cm^3  
5₅ of volume of water in Tank M at first = 5 x 8778 = 43890 cm³

Volume of water in Tank M at first = 43890 cm³

Volume of water in Tank N at first
= 22 x 19 x 23
= 9614 cm³

Total volume of water in Tank M and Tank N 
= 43890 + 9614
= 53504 cm³

Final volume of water in Tank M after 27632 cm³ of water overflowed
= 53504 - 27632
= 25872 cm³

Base area of Tank M
= 24 x 22
= 528 cm²

Height of Tank M
= 25872 ÷ 528 
= 49 cm

Answer(s): (a) 43890 cm² ; (b) 49 cm