Upper & Lower Bounds: WJEC GCSE Intermediate June 2023 Unit 1 Q16

Intermediate June 2023 Unit 1 Q16

WJECIntermediateCurrent spec3 marksUpper & Lower Bounds

16. Two time periods are measured as 4 hours 40 minutes and 2 hours 50 minutes.
Each measurement is correct to the nearest 10 minutes.

What is the least possible sum of these two time periods?
Give your answer in hours and minutes. [3]

Answer = ………… hours ………… minutes

Mark scheme

Scheme	Marks	Comments
Sight of 4(hr) 35(min) AND 2(hr) 45(min) OR Sight of 275(min) AND 165(min) OR sight of 2 × 5(min) in an appropriate calculation.	B1	Allow incorrect notation for time (e.g. 4:35 for 4(hr) 35(min)).
Valid method e.g. 4(hr) 35(min) + 2(hr) 45(min)(=6(hr) 80(min) ) 275(min) + 165(min) (= 440 (min) ) 6 (hr) 90 (min) – 10 (min) 7 (hr) 30 (min) – 10 (min) 4(hr) 40(min) + 2(hr) 50(min) – 10 (min) 280 (min) + 170 (min) – 10(min)	M1	If B0, FT provided unambiguously chosen: ‘4h 30m ≤ t₁ < 4h 40m’ and ‘2h 40m ≤ t₂ < 2h 50m’ OR ‘270m ≤ t₁ < 280m’ and ‘160m ≤ t₂ < 170m’ Allow incorrect notation for time (e.g. 4:35 for 4(hr) 35(min)).
7 (hr) 20 (min)	A1	CAO. If units are given they must be correct. Award B1M1A0 for a final answer of 6hrs 80min, 6:80 or 7:20.