AS October 2020 Q1

EdexcelAS paperCurrent spec3 marksIncludes hypothesis testingCorrelation

1. An estate agent in Tornep believes that houses further from the railway station are more expensive than those that are closer. She took a random sample of 22 three-bedroom houses in Tornep and calculated the product moment correlation coefficient between the house price and the distance from the station to be 0.3892

Stating your hypotheses clearly, use a 5% level of significance to test the estate agent’s belief. State the critical region used in your test. (3)

Mark scheme

Scheme	Marks	AO
\(\mathrm{H}_0 : \rho = 0 \qquad \mathrm{H}_1 : \rho \gt 0\)	B1	2.5
5% one-tail cv for \(r\) is: 0.3598	M1	1.1b
Significant result so there is evidence to support the agent’s belief	A1	2.2b
	(3 marks)

Notes

B1 for both hypotheses correct in terms of \(\rho\)

M1 for use of tables to find the cv of 0.3598

A1 for a correct conclusion in context mentioning “ belief ” or description of this