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2 years ago

Evaluate 4x + y for x = 5 and y = 4 * please help

Mathematics

2 answers:

Aleks [24]2 years ago

8 0

Answer:

Step-by-step explanation:

4x+y

4 times 5 is 20

then add 4

So the answer is 24.

tester [92]2 years ago

4 0

Plug in both x and y values into the equation.

4(5) + 4

20 + 4

24 is your answer. I hope this helps!

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The amount of money spent on textbooks per year for students is approximately normal.

Ostrovityanka [42]

Answer:a

$336.04 < \mu < 443.96$

The margin of error will increase

The margin of error will decreases

The 99% confidence interval is $0.4107 < p < 0.4293$

Step-by-step explanation:

From the question we are told that

The sample size $n = 19$

The sample mean is $\= x = \$\ 390$

The standard deviation is $\sigma = \$ \ 120$

Given that the confidence level is 95% then the level of significance is mathematically represented as

$\alpha = 100 - 95$

$\alpha = 5 \%$

$\alpha = 0.05$

Next we obtain the critical value of $\frac{\alpha }{2}$ from the normal distribution table

$Z_{\frac{\alpha }{2} } = 1.96$

The margin of error is mathematically represented as

$E = Z_{\frac{\alpha }{2} } * \frac{\sigma}{\sqrt{n} }$

=> $E = 1.96 * \frac{120}{\sqrt{19} }$

=> $E = 53.96$

The 95% confidence interval is

$\= x - E < \mu < \= x + E$

=> $390 - 53.96 < \mu < 390 - 53.96$

=> $336.04 < \mu < 443.96$

When the confidence level increases the $Z_{\frac{\alpha }{2} }$ also increases which increases the margin of error hence the confidence level becomes wider

Generally the sample size mathematically varies with margin of error as follows

$n \ \ \alpha \ \ \frac{1}{E^2 }$

So if the sample size increases the margin of error decrease

The sample proportion is mathematically represented as

$\r p = \frac{210}{500}$

$\r p = 0.42$

Given that the confidence level is 0.99 the level of significance is $\alpha = 0.01$

The critical value of $\frac{\alpha }{2}$ from the normal distribution table is

$Z_{\frac{\alpha }{2} } = 2.58$

Generally the margin of error is mathematically represented as

$E = Z_{\frac{\alpha }{2} }* \sqrt{ \frac{\r p (1- \r p )}{n} }$

=> $E = 0.42 * \sqrt{ \frac{0.42 (1- 0.42 )}{ 500} }$

=> $E = 0.0093$

The 99% confidence interval is

$\r p - E < p < \r p + E$

$0.42 - 0.0093 < p < 0.42 + 0.0093$

$0.4107 < p < 0.4293$

4 0

3 years ago

Can i get help plzz .....

wel

Answer:

$0.30

Step-by-step explanation:

If you already spent $5 then you have $6 remaining so you will just divide 6 and 20 and you will get 0.3 so $0.30

3 0

2 years ago

Ms. Hartline grades one math test every 1⁄4 hour. How many math tests does she grade in 2 hours? HELP QUICK!!

vazorg [7]

Answer:

8 maths tests

Step-by-step explanation:

Given data

We are told that in 1/4 hour that is 0.25hour (15 mins) She grades 1 math test

our aim is to find how many maths test she grade in 3 hours (120min)

Hence

in 15 mins she does 1 grading

in 120 mins she does x

cross multiply

15x= 120

divide both sides by 15

x= 120/15

x= 8 maths test

Hence in 2 hours, she can grade 8 maths tests

4 0

2 years ago

If a(x)=2x-4 and b(x) =x+2, which of the following expressions produces a quadratic function?

ZanzabumX [31]

Answer:

$(ab)(x)$

Step-by-step explanation:

The complete question in the attached figure

we have

$a(x)=2x-4\\b(x)=x+2$

we know that

(ab)(x) is equal to the product of a(x) and b(x)

$(ab)(x)=(2x-4)(x+2)$

Applying distributive property

$(ab)(x)=2x(x)+2x(2)-4(x)-4(2)$

$(ab)(x)=2x^2+4x-4x-8$

$(ab)(x)=2x^2-8$

This is a quadratic equation

The other expressions not produce a quadratic equation

5 0

3 years ago

I need help with multiplying polynomials using foil<br><br> Example <br> (X+5)(x-6)

MArishka [77]

Well (x+5)(×-6)
x*x =x2
x*-6=-6x
x*5 = 5x
5*-6= -30
add them all together to get x2-x-30.
I hope this is what you were asking

3 0

3 years ago