PSLE There was a total of 43015 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.
- Natalie poured 7020 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
= 39 x 30 x 4
= 4680 cm
3 Volume of water in both tanks excluding the water that is 4 cm above that of Tank Q
= 43015 - 4680
= 38335 cm
3 Base area of Tank Q
= 35 x 31
= 1085 cm
2 Base area of Tank R
= 39 x 30
= 1170 cm
2 Combined base areas of both tanks
= 1085 + 1170
= 2255 cm
2 Height of water in Tank Q
= 38335 ÷ 2255
= 17 cm
(b)
Decrease in the height of Tank R after some water was poured out
= 7020 ÷ 1170
= 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 Q
= 2 x 15
= 30 cm
Answer(s): (a) 17 cm; (b) 30 cm