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Date November 2016 Marks available 3 Reference code 16N.2.sl.TZ0.4
Level SL only Paper 2 Time zone TZ0
Command term Calculate Question number 4 Adapted from N/A

Question

A manufacturer produces 1500 boxes of breakfast cereal every day.

The weights of these boxes are normally distributed with a mean of 502 grams and a standard deviation of 2 grams.

All boxes of cereal with a weight between 497.5 grams and 505 grams are sold. The manufacturer’s income from the sale of each box of cereal is $2.00.

The manufacturer recycles any box of cereal with a weight not between 497.5 grams and 505 grams. The manufacturer’s recycling cost is $0.16 per box.

A different manufacturer produces boxes of cereal with weights that are normally distributed with a mean of 350 grams and a standard deviation of 1.8 grams.

This manufacturer sells all boxes of cereal that are above a minimum weight, w.

They sell 97% of the cereal boxes produced.

Draw a diagram that shows this information.

[2]
a.

(i)     Find the probability that a box of cereal, chosen at random, is sold.

(ii)     Calculate the manufacturer’s expected daily income from these sales.

[4]
b.

Calculate the manufacturer’s expected daily recycling cost.

[2]
c.

Calculate the value of w.

[3]
d.

Markscheme

N16/5/MATSD/SP2/ENG/TZ0/04.a/M

(A1)(A1)

 

Notes:     Award (A1) for bell shape with mean of 502.

Award (A1) for an indication of standard deviation eg 500 and 504.

 

[2 marks]

a.

(i)     0.921 (0.920968, 92.0968%)     (G2)

 

Note:     Award (M1) for a diagram showing the correct shaded region.

 

(ii)     1500×2×0.920968     (M1)

= ($) 2760 (2762.90)    (A1)(ft)(G2)

 

Note:     Follow through from their answer to part (b)(i).

 

[4 marks]

b.

1500×0.16×0.079031    (M1)

 

Notes:     Award (A1) for 1500×0.16× their (10.920968).

 

OR

(15001381.45)×0.16    (M1)

 

Notes:     Award (M1) for (1500their 1381.45)×0.16.

 

=($)19.0 (18.9676)    (A1)(ft)(G2)

[2 marks]

c.

347 (grams) (346.614)    (G3)

 

Notes:     Award (G2) for an answer that rounds to 346.

Award (G1) for 353.385 seen without working (for finding the top 3%).

 

[3 marks]

d.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
[N/A]
d.

Syllabus sections

Topic 4 - Statistical applications » 4.1 » The normal distribution.
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