AQA S1 2006 June — Question 4

Exam BoardAQA
ModuleS1 (Statistics 1)
Year2006
SessionJune
TopicNormal Distribution
TypeSingle tail probability P(X < a) or P(X > a)

4 The weights of packets of sultanas may be assumed to be normally distributed with a standard deviation of 6 grams. The weights of a random sample of 10 packets were as follows:
\(\begin{array} { l l l l l l l l l l } 498 & 496 & 499 & 511 & 503 & 505 & 510 & 509 & 513 & 508 \end{array}\)
    1. Construct a \(99 \%\) confidence interval for the mean weight of packets of sultanas, giving the limits to one decimal place.
    2. State why, in calculating your confidence interval, use of the Central Limit Theorem was not necessary.
    3. On each packet it states 'Contents 500 grams'. Comment on this statement using both the given sample and your confidence interval.
  1. Given that the mean weight of all packets of sultanas is 500 grams, state the probability that a 99\% confidence interval for the mean, calculated from a random sample of packets, will not contain 500 grams.