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3 years ago

IMPORTANT

Mathematics

2 answers:

Ludmilka [50]3 years ago

8 0

Answer:

90$

Step-by-step explanation:

180÷2=90

So Kerry earned 90$ per hour

JulsSmile [24]3 years ago

7 0

Answer: $9 an hour is how much she makes

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B. What is the probability that Teresa will pick a tile with a vowel (A, E, I, O, U) on it?

IrinaK [193]

Answer:

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Step-by-step explanation:

5 0

3 years ago

Sarah has a brother who is 5 years younger than herself and another brother who is 8 years younger than herself. She observes th

ELEN [110]

Answer:

Sarah is 13 years old

Step-by-step explanation:

Represent Sarah's age with S

Her first brother's age with F

Her second brother's age with B

So, we have:

From the first statement, we have:

$S - F = 5$ ---- (1)

From the second, we have:

$S - B = 8$ ---- (2)

The product of their ages is 40.

First, we make F the subject in (1) and B the subject in (2)

$F = S - 5$

$B = S - 8$

Their product is represented as follows:

$F * B = 40$

Substitute values for F and B

$(S - 5) * (S - 8)=40$

Open bracket

$S^2 - 5S -8S + 40 = 40$

$S^2 - 13S + 40 = 40$

Subtract 40 from both sides

$S^2 - 13S = 0$

Factorize:

$S(S - 13) = 0$

Split:

$S = 0$ or $S - 13 = 0$

But Sarah's age can't be 0 because she has two younger brothers.

So, we stick to

$S - 13 = 0$

Make S the subject

$S = 13$

<em>Hence, Sarah is 13 years old</em>

3 0

3 years ago

A journalist reported that the average amount of time that a French person spends eating lunch at a restaurant is 22 minutes. Pe

maw [93]

Answer:

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

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:

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

$t=\frac{19 -22)-(0)}{4.095\sqrt{\frac{1}{8}+\frac{1}{7}}}=-1.416$

Step-by-step explanation:

Data given

American: 21,17,17,20,25,16,20,16 (Sample 1)

French: 24,18,20,28,18,29,17 (Sample 2)

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 $\sigma^2$

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 :

$n_1 =8$ represent the sample size for group 1

$n_2 =7$ represent the sample size for group 2

$\bar X_1 =19$ represent the sample mean for the group 1

$\bar X_2 =22$ represent the sample mean for the group 2

$s_1=3.117$ represent the sample standard deviation for group 1

$s_2=5.0$ represent the sample standard deviation for group 2

First we can begin finding the pooled variance:

$S^2_p =\frac{(8-1)(3.117)^2 +(7 -1)(5.0)^2}{8 +7 -2}=16.770$

And the deviation would be just the square root of the variance:

$S_p=4.095$

And now we can calculate the statistic:

$t=\frac{19 -22)-(0)}{4.095\sqrt{\frac{1}{8}+\frac{1}{7}}}=-1.416$

Now we can calculate the degrees of freedom given by:

$df=8+7-2=13$

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

$p_v =2*P(t_{13}$

So with the p value obtained and using the significance level assumed $\alpha=0.1$ 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 10% of significance we don't have significant differences between the two means.

3 0

3 years ago

Lisa's pet shop has 2 fish tanks.Tank A contains smaller fish who are fed 1 gram of food each per day.Tank B contains 2/3 the nu

Nutka1998 [239]

Answer:

Lisa will not be able to feed both tanks the same amount of food.

Step-by-step explanation:

This question is incomplete, here is the complete question :

"Lisa pet shop has 2 fish tank . Tank A contains smaller fish who were fed 1 gram of food each per day. Tank B contains larger fish who are fed 2 gram each per day. If tank B contains 2/3 the number of fish Tank A contains,will Lisa ever feed both tanks the same amount of food."

Let the number of fish in tank A = f

Lisa fed 1 gram of food each per day = f × 1 = f

So,the number of fish in tank B = $\frac{2}{3}f$