3. An Alaskan transportation company claims to keep its box trucks warmed to at least 20°C in order to keep products from freezing during transport. The dotplot below shows the results of taking 30 SRSs of 10
temperature readings from a Normal population with u= 20 and o= 4 and recording the sample minimum
each time. Suppose 10 box trucks were randomly selected and the temperatures were measured. The sample
minimum of the temperatures of the 10 trucks was 6°C. Is there convincing evidence that the minimum
temperature is less than 20°C?
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T
T
4
02
6
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10
12
14
16
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20
Sample minimum temperature (°C)
a.
No, 6°C is a plausible value based upon the dotplot, so we cannot reject the claim made
by the company,
b. No, 6°C is not unusual. It is only 12 degrees below the expected temperature,
c. Yes, we can reject the claim made by company. It would be very surprising to get a
sample minimum of 6°C or less in an SRS of size 10 when the true sample minimum is
20°C.
d. Yes, 6°C is less than 20°C so this proves that the claim made by the company is false.
e. We cannot draw any conclusions because we do not have access to the entire population.