A-LevelMathematicsProbability and statistics9709/62 · May/June 2017 · Q15 Marks
Rani and Diksha go shopping for clothes.
- (i)Rani buys 4 identical vests, 3 identical sweaters and 1 coat. Each vest costs $5.50 and the coat costs $90. The mean cost of Rani's 8 items is $29. Find the cost of a sweater.[3]
- (ii)Diksha buys 1 hat and 4 identical shirts. The mean cost of Diksha's 5 items is $26 and the standard deviation is $0. Explain how you can tell that Diksha spends $104 on shirts.[2]
Mark scheme
Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.
- M1 An expression to work out total cost of individual items = 8 × mean, x may be implied.
- A1 Correct complete unsimplified expression / calculation
- A1 Units not required
- M1 Must see comment interpreting sd = 0, OE
- A1 See 4 x $26, $130 – $26 OE. Must have a final value of $104 stated
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