2. Si x representa la edad de Ana, ¿cómo se

The National Center for Education Statistics surveyed a random sample of 4400 college graduates about the lengths of time requir

Paha777 [63]

Answer:

95% confidence interval for the mean time required to earn a bachelor’s degree by all college students is [5.10 years , 5.20 years].

Step-by-step explanation:

We are given that the National Center for Education Statistics surveyed a random sample of 4400 college graduates about the lengths of time required to earn their bachelor’s degrees. The mean was 5.15 years and the standard deviation was 1.68 years respectively.

Firstly, the pivotal quantity for 95% confidence interval for the population mean is given by;

P.Q. = $\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }$ ~ N(0,1)

where, $\bar X$ = sample mean time = 5.15 years

$\sigma$ = sample standard deviation = 1.68 years

n = sample of college graduates = 4400

$\mu$ = population mean time

Here for constructing 95% confidence interval we have used One-sample z test statistics although we are given sample standard deviation because the sample size is very large so at large sample values t distribution also follows normal.

So, 95% confidence interval for the population mean, $\mu$ is ;

P(-1.96 < N(0,1) < 1.96) = 0.95 {As the critical value of z at 2.5%

level of significance are -1.96 & 1.96}

P(-1.96 < $\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }$ < 1.96) = 0.95

P( $-1.96 \times {\frac{\sigma}{\sqrt{n} } }$ < ${\bar X-\mu}$ < $1.96 \times {\frac{\sigma}{\sqrt{n} } }$ ) = 0.95

P( $\bar X-1.96 \times {\frac{\sigma}{\sqrt{n} } }$ < $\mu$ < $\bar X+1.96 \times {\frac{\sigma}{\sqrt{n} } }$ ) = 0.95

95% confidence interval for $\mu$ = [ $\bar X-1.96 \times {\frac{\sigma}{\sqrt{n} } }$ , $\bar X+1.96 \times {\frac{\sigma}{\sqrt{n} } }$ ]

= [ $5.15-1.96 \times {\frac{1.68}{\sqrt{4400} } }$ , $5.15+1.96 \times {\frac{1.68}{\sqrt{4400} } }$ ]

= [5.10 , 5.20]

Therefore, 95% confidence interval for the mean time required to earn a bachelor’s degree by all college students is [5.10 years , 5.20 years].

8 0

3 years ago

I need help with 4 and 5 what are the answers?

ira [324]

Answer:

4. U = 54

5. C=80

Step-by-step explanation:

Basically you move the denominator to the other side and multiply. please take note of the signs(positve, negative)

7 0

2 years ago

What percent of 146 is 39

marissa [1.9K]

Answer:

39 is 26.71% of 146

Step-by-step explanation:

Percentage solution with steps:

Step 1: We make the assumption that 146 is 100% since it is our output value.

Step 2: We next represent the value we seek with x.

Step 3: From step 1, it follows that 100% = 146.

Step 4: In the same vein, x% = 39.

Step 5: This gives us a pair of simple equations:

100% = 146(1).

x%=39(2).

Step 6: By simply dividing equation 1 by equation 2 and taking note of the fact that both the LHS (left hand side) of both equations have the same unit (%); we have

100/x% = 146/39

Step 7: Taking the inverse (or reciprocal) of both sides yields

x% / 100% = 39/146 ⇒ x= 26.71%

Therefore, 39 is 26.71% of 146.

hope it helps:)

7 0

3 years ago

I don't need an explanation, I would just like the answer to these questions

avanturin [10]

1)HGI ,S.S.S

2)DEF,A.S.A

3)C.E.D,S.A.S

6 0

3 years ago

From Midnight to 6 am the temperature rose 8 degrees C. At 6 am the temperature was -21 degrees C. What was the temperature at m

Alika [10]

Hello!

We know that from midnight to 6am the temperature went up 8° and at 6am it was -21°

To find what it was at midnight we have to work backwards

Since it went up we have to subtract 8 from -21

-21 - 8 = -29

The answer is -29°C

Hope this helps!

7 0

2 years ago

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