Question

# 1. A) The proportion of residents in Phoenix favoring the building of toll roads to complete...

1.

A) The proportion of residents in Phoenix favoring the building of toll roads to complete the freeway system is believed to be p=0.3. If a random sample of 100 individuals shows that 25 favor building toll roads do we have evidence at the 5% level to claim the true proportion is really lower?

B) A manufacturer produces crankshafts for an automobile engine. The crankshaft's diameter (3cm) is of interest because it is likely to have an impact on warranty claims. A random sample of n=15 shafts is tested and = 2.78cm' It is known that the true deviation in wear is 0.9cm and the wear is normally distributed. Is there evidence that the diameter of the crankshafts is not 3cm?

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A)

Hence, we cannot reject H0 at 5% level of significance.

There is no evidence at the 5% level to claim the true proportion is really lower than 3 cm

B)

We reject H0 if |Z|>

Hence, we cannot reject H0 at 5% level of significance.

There is NO evidence that the diameter of the crankshafts is not 3cm

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