This is the marking copy and it carries every answer. Her sheet is the other file — same numbering, same margin codes, so you can mark straight down the page.
The total mass of a box and a watermelon was 7 kg 34 g. When some strawberries were added into the box, the total mass became 8600 g. The watermelon was 3 times as heavy as all the strawberries added. Find the mass of the box, in grams.
answer 2336
method Work in grams: 7 kg 34 g = 7034 g. Adding the strawberries took the total from 7034 g to 8600 g, so the strawberries weigh 8600 − 7034 = 1566 g. The watermelon is 3 times that: 3 × 1566 = 4698 g. The box and watermelon together were 7034 g, so the box = 7034 − 4698 = 2336 g.
watch Reading 7 kg 34 g as 7340 g. It is 7000 + 34 = 7034 g — the 34 fills the ones and tens columns, not the hundreds.
Mr Lee had an apple, a papaya and a honeydew. He weighed them in pairs: apple + papaya = 730 g, apple + honeydew = 1960 g, honeydew + papaya = 2470 g. What was the mass of the honeydew, in grams?
Setup 1 apple + papaya = 730 g Setup 2 apple + honeydew = 1960 g Setup 3 honeydew + papaya = 2470 g
answer 1850
method Add all three weighings: 730 + 1960 + 2470 = 5160 g. Every fruit has been weighed exactly twice, so the three fruits together weigh 5160 ÷ 2 = 2580 g. The honeydew is the one missing from Setup 1, so honeydew = 2580 − 730 = 1850 g.
watch Subtracting two of the weighings and hoping. Adding all three and halving is what turns three pair-weights into the single total, and the rest is one subtraction.