1

Nationwide, the average waiting time until a electric utility customer service representative answers a call is 200 seconds per

Pavel [41]

Answer:

$z=\frac{120-200}{\frac{25}{\sqrt{30}}}=-17.527$

$p_v =P(Z$

If we compare the p value and the significance level given $\alpha=0.05$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis.

We can say that at 5% of significance the mean average waiting time is significantly less than 200 seconds per call.

Step-by-step explanation:

Data given and notation

$\bar X=120$ represent the sample mean

$\sigma=25$ represent the population standard deviation

$n=30$ sample size

$\mu_o =200$ represent the value that we want to test

$\alpha=0.05$ represent the significance level for the hypothesis test.

z would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the population mean is less than 200, the system of hypothesis are :

Null hypothesis: $\mu \geq 200$

Alternative hypothesis: $\mu < 200$

Since we know the population deviation, is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$z=\frac{120-200}{\frac{25}{\sqrt{30}}}=-17.527$

P-value

Since is a one-side left tailed test the p value would given by:

$p_v =P(Z$

Conclusion

If we compare the p value and the significance level given $\alpha=0.05$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis.

We can say that at 5% of significance the mean average waiting time is significantly less than 200 seconds per call.

3 0

3 years ago

A rectangle was rearranged to form a parallelogram. How is the height of the parallelogram similar to and different from the wid

Daniel [21]

A parallelogram is just a rectangle with the sides angled, it’s pretty much the same as a rectangle and all your working out should be the same as a rectangle

5 0

3 years ago

a bakery worker ordered 3,000 eggs when only 300 eggs were needed. Which explains how many more eggs were ordered than were need

Schach [20]

Answer:

2700 more eggs were ordered

4 0

3 years ago

After the closing of the mill, the town of Sawyerville experienced a decline in its population.

ycow [4]

Step-by-step explanation:

P(t) = 12,000 (2)^(-t/15)

9,000 = 12,000 (2)^(-t/15)

0.75 = 2^(-t/15)

ln(0.75) = ln(2^(-t/15))

ln(0.75) = (-t/15) ln(2)

-15 ln(0.75) / ln(2) = t

t = 6.23

5 0

3 years ago

After collecting eggs from his chickens, Dale puts the eggs into cartons to sell. Each carton holds 12 eggs. Dale fills 15 carto

riadik2000 [5.3K]

Answer: 187

Step-by-step explanation:

12*15 + 7= 187

8 0

4 years ago