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2.5.5 Hypothesis test for the mean of a normal distribution (A-level only)

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Question 62

An agricultural scientist is monitoring the yield of a specific variety of wheat. The yield per hectare is normally distributed with a standard deviation of 4.8 kg4.8\text{ kg}4.8 kg. Traditionally, the mean yield, μ\muμ, is known to be 190 kg190\text{ kg}190 kg.

The scientist suspects that a new fertilizer has increased the mean yield. She collects data from a random sample of 666 hectares and performs a hypothesis test at the 10%10\%10% significance level.

She tests H0:μ=190H_0: \mu = 190H0​:μ=190 against H1:μ>190H_1: \mu > 190H1​:μ>190.

When reviewing her notes, she finds that she has lost one of the recordings. The five available recordings are:

192.5,188.2,197.6,191.4,195.3 192.5, \quad 188.2, \quad 197.6, \quad 191.4, \quad 195.3 192.5,188.2,197.6,191.4,195.3

Given that the result of the hypothesis test was to reject the null hypothesis H0H_0H0​ at the 10%10\%10% level of significance, calculate the minimum possible value of the missing measurement, xxx. Give your answer correct to 1 decimal place.

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2.5.5 Hypothesis test for the mean of a normal distribution (A-level only) Questions

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