PSLE There was a total of 15475 cm
3 of water in rectangular tanks P and Q at first. The height of the water level in tank Q was 3 cm above that of tank P.
- Find the height of the water level in tank P.
- Zoe poured 2975 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 3 cm
= 25 x 17 x 3
= 1275 cm
3 Volume of water in both tanks excluding the water that is 3 cm above that of Tank P
= 15475 - 1275
= 14200 cm
3 Base area of Tank P
= 19 x 15
= 285 cm
2 Base area of Tank Q
= 25 x 17
= 425 cm
2 Combined base areas of both tanks
= 285 + 425
= 710 cm
2 Height of water in Tank P
= 14200 ÷ 710
= 20 cm
(b)
Decrease in the height of Tank Q after some water was poured out
= 2975 ÷ 425
= 7 cm
Original height of water before some was poured out
= 20 + 3
= 23 cm
Height of water after some was poured out
= 23 - 7
= 16 cm
Height of Tank P
= 2 x 16
= 32 cm
Answer(s): (a) 20 cm; (b) 32 cm