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3 years ago

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Mathematics

1 answer:

Novay_Z [31]3 years ago

8 0

I agree with the person above, I also believe it is B, have a nice day, Merry Christmas

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Find the ages of the people and tree

Harlamova29_29 [7]

Answer:

1. Callum = 2; Eilidh = 17; Caitlin's =22.

2. Ewan = 44; tree = 308.

Explanation:

Q1. Callum, Eilidh, and Caitlin

Let x = Callum's age

y = Eilidh's age

z = Caitlin's age

We have three conditions.

(1) x = y - 5

(2) z = y + 15

(3) x + y + z = 31

Step 1. Eliminate one of the variables in two of the equations

Subtract (1) from (2): z - x = 20

Rearrange: (4) -x + z = 20

Solve (2) for y: (5) y = z - 15

Substitute into (3): x + z - 15 + z = 31

(6) x + 2z = 46

Step 2. Set up two new equations in two variables

(5) -x + z = 20

(6) x + 2z = 46

Add (5) and (6): 3z = 66

Divide each side by 2: z = 22

Step 3. Substitute z into (5)

-x + 22 = 20

x = 2

Step 4. Substitute x into (1)

2 = y - 5

Add 5 to each side y = 7

Callum's age is 2; Eilidh's age is 7; Caitlin's age is 22.

Q2. Ewan and the tree

Let x = Ewan's age

y = tree's age

We have two conditions.

(1) y = 7x

(2) x + y = 352

Rearrange (1) (3) -7x + y = 0

(2) x + y = 352

Subtract (3) from (2) 8x = 352

Divide each side by 8 x = 44

Substitute y into (1) y = 7 × 44

y = 308

Ewan's age is 44; the tree's age is 308.

5 0

3 years ago

we believe that 42% of freshmen do not visit their counselors regularly. For this year, you would like to obtain a new sample to

Maksim231197 [3]

Answer:

A sample of 1077 is required.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

The margin of error is of:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

42% of freshmen do not visit their counselors regularly.

This means that $\pi = 0.42$

98% confidence level

So $\alpha = 0.02$ , z is the value of Z that has a pvalue of $1 - \frac{0.02}{2} = 0.99$ , so $Z = 2.327$ .

How large of a sample size is required?

A sample size of n is required, and n is found when M = 0.035. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.035 = 2.327\sqrt{\frac{0.42*0.58}{n}}$

$0.035\sqrt{n} = 2.327\sqrt{0.42*0.58}$

$\sqrt{n} = \frac{2.327\sqrt{0.42*0.58}}{0.035}$

$(\sqrt{n})^2 = (\frac{2.327\sqrt{0.42*0.58}}{0.035})^2$

$n = 1076.8$

Rounding up:

A sample of 1077 is required.

3 0

3 years ago

Please help! I will mark as brainliest IF answer is right. <3

EastWind [94]

Answer:

b^2 + 3b - 4 + 4/(b-2)

Step-by-step explanation:

see pic

7 0

2 years ago

Read 2 more answers

Do the ratios 2:4 and 5:10 form a proportion?<br> yes or no

Kisachek [45]

Answer:

Yes, the ratios do form a proportion.

5 0

2 years ago

Officer Brimberry wrote 24 tickets for traffic violations last week, but only 21 tickets this week. What is the percent decrease

IrinaVladis [17]

Answer:3 percent because

5 0

3 years ago