4. A cell phone manufacturer claims that their newly designed cellular phone battery is more consistent in battery life

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4. A cell phone manufacturer claims that their newly designed
cellular phone battery is
more consistent in battery life (measured in hours of life before
the charge is depleted)
than its previous model. The previous model had standard deviation
2.1 hours. A sample
is taken from the new model of batteries. In 30 batteries tested,
the standard deviation of
the sample was 1.7 hours. Assume the population of battery life is
normally distributed.
Test the company’s claim at significance level α = 0.05 and
interpret the result.