PSLE There was a total of 29212 cm
3 of water in rectangular tanks Q and R at first. The height of the water level in tank R was 4 cm above that of tank Q.
- Find the height of the water level in tank Q.
- Gabby poured 7714 cm3 of water out of tank R. Tank R was then half filled with water. What was the height of tank R?
(a)
Volume of water in Tank R with a height of 4 cm
= 38 x 29 x 4
= 4408 cm
3 Volume of water in both tanks excluding the water that is 4 cm above that of Tank Q
= 29212 - 4408
= 24804 cm
3 Base area of Tank Q
= 31 x 26
= 806 cm
2 Base area of Tank R
= 38 x 29
= 1102 cm
2 Combined base areas of both tanks
= 806 + 1102
= 1908 cm
2 Height of water in Tank Q
= 24804 ÷ 1908
= 13 cm
(b)
Decrease in the height of Tank R after some water was poured out
= 7714 ÷ 1102
= 7 cm
Original height of water before some was poured out
= 13 + 4
= 17 cm
Height of water after some was poured out
= 17 - 7
= 10 cm
Height of Tank Q
= 2 x 10
= 20 cm
Answer(s): (a) 13 cm; (b) 20 cm