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3 years ago

Give 4 integers whose product is less than zero and whose sum is -28

1 answer:

3 0

5 integers whose product is less than zero and whose sum is 17 ... product, so just use one -1, and pick 4 positive integers that have sum 18.

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Tom drove 130 Miles at the speed of 65 mph, and then 200 more miles at the speed of 30 mph. What was his average speed for the e

ch4aika [34]

47.5 mph- because 30+65 equals 95 and 95 divided by 2 is 47.5

7 0

3 years ago

Consider independent simple random samples that are taken to test the difference between the means of two populations. The varia

Arturiano [62]

Answer:

d. t distribution with df = 80

Step-by-step explanation:

Assuming this problem:

Consider independent simple random samples that are taken to test the difference between the means of two populations. The variances of the populations are unknown, but are assumed to be equal. The sample sizes of each population are n1 = 37 and n2 = 45. The appropriate distribution to use is the:

a. t distribution with df = 82.

b. t distribution with df = 81.

c. t distribution with df = 41.

d. t distribution with df = 80

Solution to the problem

When we have two independent samples from two normal distributions with equal variances we are assuming that

$\sigma^2_1 =\sigma^2_2 =\sigma^2$

And the statistic is given by this formula:

$t=\frac{(\bar X_1 -\bar X_2)-(\mu_{1}-\mu_2)}{S_p\sqrt{\frac{1}{n_1}+\frac{1}{n_2}}}$

Where t follows a t distribution with $n_1+n_2 -2$ degrees of freedom and the pooled variance $S^2_p$ is given by this formula:

$\S^2_p =\frac{(n_1-1)S^2_1 +(n_2 -1)S^2_2}{n_1 +n_2 -2}$

This last one is an unbiased estimator of the common variance $\sigma^2$

So on this case the degrees of freedom are given by:

$df= 37+45-2=80$

And the best answer is:

d. t distribution with df = 80

5 0

3 years ago

Convert 498,000 into scientific notation

Paladinen [302]

Hello! The answer to your question would be as followed:

4.98 x 10^5

8 0

3 years ago

Read 2 more answers

Write the equation of the line that passes through the points (−7,5) and (-7,-8).

Viefleur [7K]

Answer:

x = -7

Step-by-step explanation:

First we find the slope using

m = ( y2-y1)/(x2-x1)

= ( -8 - 5)/( -7 - -7)

= (-8-5)/(-7+7)

= -13/0

This means the slope is undefined and the line is vertical

Vertical lines are in the form

x= constant and the constant is the x value of the points

x = -7

3 0

2 years ago

Researchers studying the acquisition of pronunciation often compare measurements made on the recorded speech of adults and child

dolphi86 [110]

Answer:

(A) The additional information that is needed to confirm about the conditions for this test have been met is ‘Population is approximately normal.

(B) The test statistic = 1.9965

(C1) P-value = 0.0556

(C2) There is no significant difference between mean VOT for children and adults.

D1) It is possible to make type II error.

(D2) There should be a difference in the VOT of adults and children.

Step-by-step explanation:

Let na be the number of adults = 20

xa mean VOT for adults = 88.17

sa standard deviatiation of VOT for adults = 24.74

Let nc be the number of children = 10

xc mean VOT for children =60.67

sc standard deviatiation of VOT for children = 39.89

(A) From the information the population variances are unknown and the two sample are assumed to be independent and the sample the sample size are smaller that is (n<30).

This indicates that the additional information that is required for the conditions of the test to be satisfied is 'distribution of the population'. the addition assumption to be made is, that the population distribution is normal.

(b) Calculating the test statistics using the formula;

t = (xa -xc)/SE - d

where SE = standard deviation , d= hypothesized difference = 0

But SE = √sa²/na +sc²/nc

= √24.74 ²/20 + 39.89²/10

= √189.72559

= 13.774

Substituting into test statistics equation, we have

t = (xa -xc)/SE - d

= (88.17 - 60.67/13.774

= 1.9965

Therefore the test statistic is 1.9965

Degree of freedom = na + nc -2

= 10+ 20 -2

= 28

The p-value for t=1.9965 at 28 degrees of freedom and 0.05 level of significance is 0.0556.

The p-value 0.0556 is greater than given level of significance 0.05 hence we fail to reject the null hypothesis and conclude that there is no significant difference between mean VOT for children and adults.

(D1) From the information in part (C) the null hypothesis is not rejected.

Since the null hypothesis is not rejected, there might be a chance that not rejecting null hypothesis would be wrong. In this type of situation the error that can occur would be type II error.

(D2) The type of error describe in the context of this study is obtained by the concept of the type II error which tells that the null hypothesis is not rejected when it is actually false.

7 0

3 years ago