Date | November 2020 | Marks available | 4 | Reference code | 20N.2.AHL.TZ0.H_9 |
Level | Additional Higher Level | Paper | Paper 2 | Time zone | Time zone 0 |
Command term | Determine | Question number | H_9 | Adapted from | N/A |
Question
The weights, in grams, of individual packets of coffee can be modelled by a normal distribution, with mean 102 g and standard deviation 8 g.
Find the probability that a randomly selected packet has a weight less than 100 g.
The probability that a randomly selected packet has a weight greater than w grams is 0.444. Find the value of w.
A packet is randomly selected. Given that the packet has a weight greater than 105 g, find the probability that it has a weight greater than 110 g.
From a random sample of 500 packets, determine the number of packets that would be expected to have a weight lying within 1.5 standard deviations of the mean.
Packets are delivered to supermarkets in batches of 80. Determine the probability that at least 20 packets from a randomly selected batch have a weight less than 95 g.
Markscheme
* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.
Χ~N(102,
(M1)A1
[2 marks]
(M1)
A1
[2 marks]
(M1)
(A1)
A1
[3 marks]
EITHER
(A1)
OR
(A1)
THEN
(M1)
A1
[3 marks]
(A1)
recognising (M1)
now using (M1)
A1
[4 marks]