The graph below shows the amount of salt, in grams, purchased per person per week in England between 2001-02 and 2014, based upon the Large Data Set.
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Meera and Gemma are arguing about what this graph shows.
Meera believes that the amount of salt consumed by people decreased greatly during this period.
Gemma says that this is not the case.
Using your knowledge of the Large Data Set, give two reasons why Gemma may be correct. [0pt]
[2 marks]
16
It is known that the mean amount of sugar purchased per person in England in 2014 was 78.9 grams, with a standard deviation of 25.0 grams.
In 2018, a sample of 918 people had a mean of 80.4 grams of sugar purchased per person.
Investigate, at the \(5 \%\) level of significance, whether the mean amount of sugar purchased per person in England has changed between 2014 and 2018.
Assume that the survey data is a random sample taken from a normal distribution and that the standard deviation has remained the same.
16
Another test is performed to determine whether the mean amount of fat purchased per person has changed between 2014 and 2018.
At the \(10 \%\) significance level, the null hypothesis is rejected.
With reference to the \(10 \%\) significance level, explain why it is not necessarily true that there has been a change. [0pt]
[2 marks]
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