PSLEThe graph shows the mass of a glass when empty and when different combinations of objects P, Q and R are placed in the glass.
- What is the mass of the empty glass?
- What is the average mass of the objects P, Q and R?
(a)
Mass of the empty glass = 170 g
(b)
Mass of P and R
= 490 - 170
= 320 g
Mass of P and Q
= 460 - 170
= 290 g
Mass of Q and R
= 400 - 170
= 230 g
(P + R) + (P + Q) + (Q + R) = 320 + 290 + 230
2 P + 2 Q + 2 R = 840
2 x (P + Q + R) = 840
P + Q + R
= 840 ÷ 2
= 420 g
Average mass of the objects P, Q and R
= 420 ÷ 3
= 140 g
Answer(s): (a) 170 g; (b) 140 g