PSLE There was a total of 14259 cm
3 of water in rectangular tanks P and Q at first. The height of the water level in tank Q was 2 cm above that of tank P.
- Find the height of the water level in tank P.
- Natalie poured 2250 cm3 of water out of tank Q. Tank Q was then half filled with water. What was the height of tank Q?
(a)
Volume of water in Tank Q with a height of 2 cm
= 25 x 15 x 2
= 750 cm
3 Volume of water in both tanks excluding the water that is 2 cm above that of Tank P
= 14259 - 750
= 13509 cm
3 Base area of Tank P
= 21 x 16
= 336 cm
2 Base area of Tank Q
= 25 x 15
= 375 cm
2 Combined base areas of both tanks
= 336 + 375
= 711 cm
2 Height of water in Tank P
= 13509 ÷ 711
= 19 cm
(b)
Decrease in the height of Tank Q after some water was poured out
= 2250 ÷ 375
= 6 cm
Original height of water before some was poured out
= 19 + 2
= 21 cm
Height of water after some was poured out
= 21 - 6
= 15 cm
Height of Tank P
= 2 x 15
= 30 cm
Answer(s): (a) 19 cm; (b) 30 cm