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Makovka662 [10]

3 years ago

10

A battery was charged. When the changing began, it was 23 percent full. After 30 minutes of charging, the battery was 89 percent

full? How long did it take to fully charge in minutes?

1 answer:

Karo-lina-s [1.5K]3 years ago

5 0

Attached the solution and work.

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A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies. Random

Yuliya22 [10]

Answer:

b) independent samples t-test

$t=\frac{(5.92 -5.74)-(0)}{\sqrt{\frac{1.88^2}{5}}+\frac{1.81^2}{5}}=0.154$

$p_v =2*P(t_{8}>0.154) =0.881$

So with the p value obtained and using the significance level given $\alpha=0.05$ we have $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can said that at 5% of significance the mean of the group 1 (boys) is NOT significantly different than the mean for the group 2 (Girls).

Step-by-step explanation:

The system of hypothesis on this case are:

Null hypothesis: $\mu_1 = \mu_2$

Alternative hypothesis: $\mu_1 \neq \mu_2$

Or equivalently:

Null hypothesis: $\mu_1 - \mu_2 = 0$

Alternative hypothesis: $\mu_1 -\mu_2\neq 0$

Our notation on this case :

$n_1 =5$ represent the sample size for group 1

$n_2 =5$ represent the sample size for group 2

We can calculate the mean and deviation for eaach group with the following formulas:

$\bar X= \frac{\sum_{i=1}^n X_i}{n}$

$s = \sqrt{\frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}}$

$\bar X_1 =5.92$ represent the sample mean for the group 1

$\bar X_2 =5.74$ represent the sample mean for the group 2

$s_1=1.88$ represent the sample standard deviation for group 1

$s_2=1.81$ represent the sample standard deviation for group 2

If we see the alternative hypothesis we see that we are conducting a bilateral test and with independnet samples t test.

b) independent samples t-test

The statistic is given by this formula:

$t=\frac{(\bar X_1 -\bar X_2)-(\mu_{1}-\mu_2)}{\sqrt{\frac{s^2_1}{n_1}}+\frac{S^2_2}{n_2}}$

And now we can calculate the statistic:

$t=\frac{(5.92 -5.74)-(0)}{\sqrt{\frac{1.88^2}{5}}+\frac{1.81^2}{5}}=0.154$

The degrees of freedom are given by:

$df=5+5-2=8$

And now we can calculate the p value using the altenative hypothesis:

$p_v =2*P(t_{8}>0.154) =0.881$

So with the p value obtained and using the significance level given $\alpha=0.05$ we have $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can said that at 5% of significance the mean of the group 1 (boys) is NOT significantly different than the mean for the group 2 (Girls).

7 0

3 years ago

A football team gained 5 yards, lost 8 yards, lost another 2 yards, and then gained 45 yards. What were the total yards gained o

Fudgin [204]

Answer:

yes you would be correct if they started with zero yards at the beginning

Step-by-step explanation:

6 0

3 years ago

Matt plans to put concrete on a rectangular portion of his driveway. The portion is 8 feet long and 4 inches high. The price of

Lubov Fominskaja [6]

length = 8ft
height = 4 in
width = w ft --> u looking for this

convert in to ft for the height:

4 in (1 ft / 12 in) = 1/3 ft

You know that:
1 cubic yard = $ 98
? cubic yard = $58.07

Solve for ? cubic yard:
? cubic yard = 58.07/98 = 0.592551

convert this in cubic feet:
1 yard = 3 feet
0.59255 cubic yard (27 cubic ft/1 cubic yard) = 15.99887755 cubic ft

Now solve for the width:
length x width x height = ? cubic ft.
width = ? cubic ft / (length x height) =15.99887755 cubic ft/[(8ft)(1/3 ft )] = 5.999579082 ft

approx 6 ft

4 0

3 years ago

What is the solution to the equation 9(x − 1) = 27? (1 point) x = 2.5 x = 0.5 x = −0.5 x = −3.5

Tems11 [23]

Step-by-step explanation:

Are you sure you wrote the answers correctly?

7 0

3 years ago

Read 2 more answers

1/6×2/3<br> show me how to do it

hodyreva [135]

Multiple 6 with 3 and 1 with 2
2/18 = 19

7 0

3 years ago