when engaging in weight control (fitness/fat burning) types of exercise, a person is expected to attain about 60% of their maximum heart rate. for 20-year-olds, this rate is approximately 120 bpm. a simple random sample of 100 20-year-olds was taken, and the sample mean was found to be 107 bpm with a standard deviation of 45 bpm. researchers wonder if this is evidence to conclude that the expected level is actually lower than 120 bpm. to determine this, we test the following hypotheses suppose the mean and standard deviation obtained were based on a sample of size 25 rather than 100. the p-value would be

Respuesta :

There is sufficient data to prove that the heart rate was less than 120 beats per minute (P-value = 0.002).

For the population mean weight control heart rate of 20-year-olds, the 95% confidence interval is (98.07, 115.93).

Step-by-step explanation:

This is a test of the population mean's theory.

The assertion is that a heart rate of less than 120 bpm exists.

The alternative and null hypothesis are then:

h0 : μ = 120

ha : μ < 120

The level of significance is 0.05.

The sample has a n=100 size.

M=107 is the sample mean.

Due to the unknown population standard deviation, we estimate it using the sample standard deviation, which has a value of s=45.

Using the following formula, the estimated standard error of the mean is calculated:

Sm = [tex]\frac{s}{\sqrt{n} }[/tex]= [tex]\frac{45}{\sqrt{100} }[/tex] = 4.5

The t-statistic can then be calculated as follows:

T = [tex]\frac{m-μ}{\frac{s}{\sqrt{n} } }[/tex] = 107-120/4.5 = -13/4.5 -2.88

The t-statistic can then be calculated as follows:

df= n-1 = 100-1 = 99

These sample size's degrees of freedom are:

Given that this test has 99 degrees of freedom, a left-tailed design, and a t value of -2.889, the P-value is determined as follows (using a t-table)

p-value = p(t<-2.88)= 0.002

The effect is significant because the P-value (0.002) is less than the 0.05 level of significance.

The naive theory is disproved.

There is sufficient proof to back up the assertion that the heart rate was less than 120 bpm.

A 95% confidence interval for the mean must be calculated.

Since the population standard deviation is unknown, we must infer it from the sample standard deviation in order to get the critical number using a t-students distribution.

M=107 is the sample mean.

N=100 is the sample size.

When σ is unknown, an estimation of σM is made by dividing s by the square root of N:

Sm =[tex]\frac{s}{\sqrt{N} }[/tex] =[tex]\frac{45}{\sqrt{100} }[/tex] =4.5

The t-value for a 95% confidence interval is t=1.984.

The margin of error (MOE) can be calculated as:

MOE = t*Sm = 1.984 * 4.5 = 8.92

Then, the lower and upper bounds of the confidence interval are:

LL = M - t*Sm = 107- 8.92 = 98.07

UL = M +t *Sm = 107 + 8.92 = 115.93

The 95% confidence interval for the population mean weight control heart rate of 20-year-olds is (98.07, 115.93).

To learn more about T-statistic:

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