Find the value of x (3x-9) (x + 7)

How do we solve for x

blondinia [14]

X/2 + 5 = -10
x/2 = -10 - 5
x/2 = -15
x = -15(2)
x = -30

3 0

2 years ago

Joan had 227 dollars to spend on 8 books. After buying them she had 11 dollars. How

Eddi Din [679]

The correct answer is 27

6 0

3 years ago

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

What is y+0.4=2? help please

sveticcg [70]

Y + 0.4 = 2 .....subtract 0.4 from both sides
y = 2 - 0.4
y = 1.6 <==

8 0

3 years ago

Read 2 more answers

What happens to the value of the expression as 50/p decreases from a large positive number to a small positive number?

Pepsi [2]

Answer:

50/p increases from a small positive number to a big positive number.

Step-by-step explanation:

p is in the denominator. This means that p and the value of the expression 50/p are inverse proportional. So for a big value of p, 50/p has a small positive value. For a small value of p, 50/p has a high positive value.

what happens to the value of the expression 50/p as p decreases from a large positive number to a small positive number?

50/p increases from a small positive number to a big positive number.

For example

50/1000 = 0.05

50/1 = 50

7 0

2 years ago