The figure shows the amount of water in two rectangular tanks, F and G, at first. Riordan poured ¹₃ of the water from F into G to fill it to the top, without overflowing.

1. How much water was there in Tank F at first?
2. Riordan then poured all the water from Tank G into Tank F. 1800 cm³ of water overflowed from Tank F. What was the height of Tank F?

(a)
Volume of water to fill Tank G
= 18 x 15 x 14
= 3780 cm<sup>3

1</sup>₃ of volume of water in Tank F at first = 3780 cm^3  
3₃ of volume of water in Tank F at first = 3 x 3780 = 11340 cm³

Volume of water in Tank F at first = 11340 cm³

Volume of water in Tank G at first
= 18 x 15 x 18
= 4860 cm³

Total volume of water in Tank F and Tank G 
= 11340 + 4860
= 16200 cm³

Final volume of water in Tank F after 1800 cm³ of water overflowed
= 16200 - 1800
= 14400 cm³

Base area of Tank F
= 20 x 18
= 360 cm²

Height of Tank F
= 14400 ÷ 360 
= 40 cm

Answer(s): (a) 11340 cm² ; (b) 40 cm