A fishmonger weighs two packets of prawns, packet X and packet Y. Packet X weighs 1720 kg and packet Y weighs 1.85 kg. Packet Z, a third packet, weighs 2.6 kg. Answer each part.
- Write 1720 kg as a decimal, in kg. [1 mark]
- Find the total mass of packets X and Y. Give your answer as a mixed number in simplest form, in kg. [2 marks]
- How much lighter is packet Z than the total mass in part (b)? Give your answer as a fraction in simplest form, in kg. [2 marks]
Need a hint?
For (a), change 7/20 to hundredths first. For (b), add in decimals, then change the answer to a mixed number. For (c), use your answer from (b) and subtract 2.6, then write the decimal as a fraction.
Worked answer
- (a) 7/20 = 35/100 = 0.35, so 1720 = 1.35 kg.
- (b) 1.35 + 1.85 = 3.20 kg.
- (b) 3.20 = 315 kg.
- (c) Total from (b) is 3.2 kg, so 3.2 − 2.6 = 0.6 kg.
- (c) 0.6 = 610 = 35 kg in simplest form.
The mistake this question tests
Simplest form in final fraction answers
Pupils who read 7/20 as 0.7 (or 0.07) in part (a) get the decimal wrong, and every later part fails with it. Pupils who write 0.6 in part (c) and stop have not given the fraction the question asks for.
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