An equation is shown. x + 3 = 8.5 what is the solution to the equation

A used bookstore sells hardback books and paperback books.A hardback book costs $11, including tax.A paperback book costs $5, in

Ket [755]

Answer:

D.5

Step-by-step explanation:

You can write the following equations from the information given:

y=x+3 (1)

11x+5y=47 (2)

x is the number of hardback books

y is the number of paperback books

You can replace (1) in (2):

11x+5(x+3)=47

11x+5x+15=47

16x=47-15

16x=32

x=32/16

x=2

Then, you can replace the value of x in (1) to find the value of y:

y=2+3

y=5

According to this, the answer is that Jamal bought 5 paperback books.

6 0

3 years ago

Polymer composite materials have gained popularity because they have high strength to weight ratios and are relatively easy and

Brums [2.3K]

Answer:

$t=\frac{51.6-48}{\frac{1.1}{\sqrt{10}}}=10.349$

$p_v =P(t_9>10.349)=1.34x10^{-6}$

If we compare the p value and the significance level given for example $\alpha=0.05$ we see that $p_v$ so we can conclude that we reject the null hypothesis, and the the actual mean is significantly higher than 48 MPa at 5% of significance.

Step-by-step explanation:

1) Data given and notation

$\bar X=51.6$ represent the sample mean

$s=1.1$ represent the standard deviation for the sample

$n=10$ sample size

$\mu_o =48$ represent the value that we want to test

$\alpha=0.05$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to determine if the mean score is higher than 48, the system of hypothesis would be:

Null hypothesis: $\mu \geq 48$

Alternative hypothesis: $\mu > 48$

We don't know the population deviation, so for this case is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$t=\frac{51.6-48}{\frac{1.1}{\sqrt{10}}}=10.349$

Calculate the P-value

First we find the degrees of freedom:

$df=n-1=10-1=9$

Since is a one-side upper test the p value would be:

$p_v =P(t_9>10.349)=1.34x10^{-6}$

Conclusion

If we compare the p value and the significance level given for example $\alpha=0.05$ we see that $p_v$ so we can conclude that we reject the null hypothesis, and the the actual mean is significantly higher than 48 MPa at 5% of significance.

5 0

3 years ago

What is the square root of 81

Kay [80]

The square root of 81 is 9
Your answer is <em>9
</em>Work:
9 x 9 = 81

7 0

3 years ago

Read 2 more answers

This is a problem involving absolute value<br> |-3| - |-17| =

den301095 [7]

That means the same as 3-17 so the answer is -14

7 0