Question

The amount of time workers spend commuting to their jobs each day in a large metropolitan city has a mean of 70 minutes and a standard deviation of 20 minutes. Assuming nothing is known about the shape of the distribution of commuting times, what percentage of these commuting times are between 30 and 110 minutes

Answer 1

Answer:

At least 75% of these commuting times are between 30 and 110 minutes

Step-by-step explanation:

Chebyshev Theorem

The Chebyshev Theorem can also be applied to non-normal distribution. It states that:

At least 75% of the measures are within 2 standard deviations of the mean.

At least 89% of the measures are within 3 standard deviations of the mean.

An in general terms, the percentage of measures within k standard deviations of the mean is given by $100(1 - \frac{1}{k^{2}})$.

In this question:

Mean of 70 minutes, standard deviation of 20 minutes.

Since nothing is known about the distribution, we use Chebyshev's Theorem.

What percentage of these commuting times are between 30 and 110 minutes

30 = 70 - 2*20

110 = 70 + 2*20

THis means that 30 and 110 minutes is within 2 standard deviations of the mean, which means that at least 75% of these commuting times are between 30 and 110 minutes