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Nana76
1 month ago
3

A company that manufactures laptop batteries claims the mean battery life is 16 hours. Assuming the distribution of battery life

is approximately normal, a consumer group will conduct a hypothesis test to investigate whether the battery life is less than 16 hours. The group selected a random sample of 14 of the batteries and found an average life of 15.6 hours with a standard deviation of 0.8 hour.
Which of the following is the correct test statistic for the hypothesis test?

A. t=15.6−160.8
B. t=16−15.60.8
C. t=15.6−160.813
D. t=15.6−160.814
E. t=16−15.60.814
Mathematics
1 answer:
Svet_ta [12.4K]1 month ago
3 0

Answer:

The appropriate test statistic for the hypothesis test is t = -1.87

Step-by-step explanation:

The null hypothesis is:

H_{0} = 16

The alternative hypothesis is:

H_{1} < 16

The test statistic is:

t = \frac{X - \mu}{\frac{s}{\sqrt{n}}}

In this equation, X signifies the sample mean, \mu denotes the value under the null hypothesis, s is the standard deviation of the sample, and n represents the sample size.

In this scenario:

X = 15.6, \mu = 16, s = 0.8, n = 14

Thus

t = \frac{X - \mu}{\frac{s}{\sqrt{n}}}

t = \frac{15.6 - 16}{\frac{0.8}{\sqrt{14}}}

t = -1.87

The correct test statistic for the hypothesis test is t = -1.87

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J.J.Bean sells a wide variety of outdoor equipment and clothing. The company sells both through mail order and via the internet.
babunello [11511]

The 99% confidence interval for the actual mean difference between average mail-order and internet purchase amounts falls within [$(-31.82), $12.02].

Step-by-step clarification:

We know a random sample of 16 mail-order sales receipts shows a mean sale amount of $74.50 and a standard deviation of $17.25.

For internet sales, a random sample of 9 receipts gives a mean sale amount of $84.40 with a standard deviation of $21.25.

The pivotal value utilized for constructing a 99% confidence interval for the true mean difference is given by;

                      P.Q.  =  

 ~

where,

= sample mean of mail-order sales = $74.50 \frac{(\bar X_1-\bar X_2)-(\mu_1-\mu_2)}{s_p \times \sqrt{\frac{1}{n_1}+\frac{1}{n_2} } }t__n_1_+_n_2_-_2

= sample mean of internet sales = $84.40

\bar X_1 = standard deviation for mail-order sales = $17.25

\bar X_2 = standard deviation for internet sales = $21.25

s_1 = number of mail-order sales receipts = 16

= number of internet sales receipts = 9s_2

Furthermore,  

 =  n_1 = 18.74

n_2

The actual mean difference between average mail-order and internet purchases is denoted by (s_p =\sqrt{\frac{(n_1-1)\times s_1^{2}+(n_2-1)\times s_2^{2} }{n_1+n_2-2} }\sqrt{\frac{(16-1)\times 17.25^{2}+(9-1)\times 21.25^{2} }{16+9-2} }

).

Thus, the 99% confidence interval for (\mu_1-\mu_2) is expressed as;

      = \mu_1-\mu_2 Here, the t critical value at the 0.5% significance level with 23 degrees of freedom is 2.807.           =

          = [$-31.82, $12.02](\bar X_1-\bar X_2) \pm t_(_\frac{\alpha}{2}_) \times s_p \times \sqrt{\frac{1}{n_1} +\frac{1}{n_2}}

Therefore, the 99% confidence interval for the true mean difference between average mail-order and internet purchases is [$(-31.82), $12.02].

(74.50-84.40) \pm (2.807 \times 18.74 \times \sqrt{\frac{1}{16} +\frac{1}{9}})

5 0
28 days ago
Dr. Shah visits patients at their homes. The equation y = 150x + 50 represents the amount
Zina [12198]

Answer:

50

Step-by-step clarification:

The equation that represents the total cost is in the format of a linear equation y = mx + c

Here, m signifies the slope of the line

c indicates the y-intercept, showing where the line intersects the y-axis

When the equation y = 150x + 50 is plotted, it will form a linear graph where the y-intercept corresponds to 50, as observed in the standard form of a linear equation.

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Justin wants to buy plants for his property, and he can afford to spend at most $480. The local nursery sells holly bushes for $
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Answer: 10 holly bushes and 12 bayberry shrubs

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According to a survey by Bankrate, of adults in the United States save nothing for retirement (CNBC website). Suppose that adult
tester [12085]

Complete Question

The complete question appears in the first uploaded image

Answer:

a) Yes, selecting 15 corresponds to a binomial experiment

b)

c)

d) P(r = 15) = 3.2768 *10^{-11}

Step-by-step explanation:

Regarding question a:

For an experiment to qualify as binomial

the trials have to be independent

each trial must yield one of two possible outcomes

Given that the selection of 15 individuals is random, we ascertain that the trials are independent and the outcomes are “either the individual saves for retirement or does not save for retirement.”

Therefore, we conclude that the selection of 15 people at random is indeed a binomial experiment.

In question b:

The probability that all selected adults do not save for retirement is mathematically modeled as

P(r = n) = ^nC_r * p^r * q^{n-r}

Here C signifies combination

r = 15 implies all selected adults

n refers to the population size equating to 15

From the problem, p = 0.20

and q can be calculated as

=>

=> q = 1 - p

Thus

P(r = 15) = ^{15}C_{15} * p^{15} * q^{15-15}

P(r = 15) = 3.2768 *10^{-11} Regarding question c:

The probability that exactly five of the selected adults do not save for retirement is mathematically modeled as

P(r = 5) = ^{15} C_5 * (0.20)^5 * (0.80)^{15}

P(r = 5) = 0.1032

In relation to question d:

The probability that at least one of the selected adults opts not to save for retirement can be mathematically expressed as

P(r \ge 1 ) = 1 - P (r = 0 )

P(r \ge 1 ) = 1 - [ ^{15} C _ 0 * (0.20)^{0} * (0.80 )^{15}]

P(r \ge 1 ) = 1 - 0.0352

P(r \ge 1 ) = 0.9648

4 0
28 days ago
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