PSLE There was a total of 20029 cm
3 of water in rectangular tanks P and Q at first. The height of the water level in tank Q was 4 cm above that of tank P.
- Find the height of the water level in tank P.
- Cathy poured 3906 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 4 cm
= 31 x 21 x 4
= 2604 cm
3 Volume of water in both tanks excluding the water that is 4 cm above that of Tank P
= 20029 - 2604
= 17425 cm
3 Base area of Tank P
= 22 x 17
= 374 cm
2 Base area of Tank Q
= 31 x 21
= 651 cm
2 Combined base areas of both tanks
= 374 + 651
= 1025 cm
2 Height of water in Tank P
= 17425 ÷ 1025
= 17 cm
(b)
Decrease in the height of Tank Q after some water was poured out
= 3906 ÷ 651
= 6 cm
Original height of water before some was poured out
= 17 + 4
= 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) 17 cm; (b) 30 cm