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Novosadov [1.4K]

2 years ago

13

erin has $50. she wants to purchase a cell phone ($20) and spend the rest in music cds each cd costs $8. write an inepuality for

the number of music CDs she can purchase.

1 answer:

HACTEHA [7]2 years ago

3 0

She can buy 3 because 50-20=30 30/8=3.75 so u round down cause you don't have enough money to buy 4

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Which expressions are equivalent to 4b4b ? Choose all answers that apply: Choose all answers that apply: (Choice A) A b+2(b+2b)b

NeX [460]

Answer: B) $3b+b$

C) $2(2b)$

Step-by-step explanation:

$\text{ A) }b+2(b+2b) = b+ 2(3b) = b + 6b = 7b$

$\text{ B) }3b+b = (3+1)b = 4b$

$\text{ C) }2(2b) = 4b$

Thus, Option B and C is giving the result 4b,

Therefore, they are the expressions that are equivalent to 4b.

5 0

2 years ago

Read 2 more answers

Which are solutions of x2 + 5x = 2? Check all that<br> apply.

strojnjashka [21]

Answer:

x=-5/2+-√33/2

Step-by-step explanation:

x^2+5x=2

you then solve by completing the square using the formula (b/2)^2 in order to create the new term. Solve for x by using this term to complete the square.

Your answer is then

x=-5/2+-√33/2

7 0

2 years ago

Deepak is a landscaper who charges $30 for each job he does plus an additional $15 for each hour he works. He only accepts jobs

BartSMP [9]

Answer:

$30+15x\geq 90$

Step-by-step explanation:

Deepak charges for each Job = $30

An additional charges for working each hour = $15

Let x be the number of hours he worked for each job.

So,additional charges for working x hours = 15 x

So,he earns in total at each job = $30+15x$

We are also given that He only accepts jobs if he will earn at least $90 the job.

This means he must earn $90 or more than that .

So, the inequality becomes:

$30+15x\geq 90$

Hence an inequality to determine x, the number of hours he must work during each job in order to accomplish this is $30+15x\geq 90$

4 0

2 years ago

Read 2 more answers

BOXES Simon will make a box without a top by cutting out corners of equal size from a 22 inch by 15 inch sheet of cardboard and

il63 [147K]

Answer:

Volume of box is $432 in^3$

Step-by-step explanation:

Let x be the side of square corner

Length of box after cutting corners =22-2x

Breadth of box after cutting corners =15-2x

Height =x

Volume of box = (22-2x)(15-2x)x

Volume of box = $4x^3-74x^2+330x$

Differentiate w.r.t x

$\frac{dV}{dx}=12x^2-148x+330$

Substitute derivative =0

$12x^2-148x+330=0\\x=\frac{37-\sqrt{379}}{6},\frac{37+\sqrt{379}}{6}\\\frac{d^2V}{dx^2}=24x-148$

at $x=\frac{37-\sqrt{379}}{6}$

$\frac{d^2V}{dx^2}=24x-148=24(\frac{37-\sqrt{379}}{6} )-148=-77.87 < 0$ hence maximum

at $x=\frac{37+\sqrt{379}}{6}$

$\frac{d^2V}{dx^2}=24x-148=24(\frac{37+\sqrt{379}}{6} )-148=77.87>0$ hence minimum

So,Volume of box = $4x^3-74x^2+330x=4(\frac{37-\sqrt{379}}{6} )^3-74(\frac{37-\sqrt{379}}{6} )^2+330(\frac{37-\sqrt{379}}{6} )=432.23 in^3$

Hence Volume of box is $432 in^3$

4 0

2 years ago

Customers arrive at a movie theater at the advertised movie time only to find that they have to sit through several previews and

lubasha [3.4K]

This question is incomplete, the complete question is;

Customers arrive at a movie theater at the advertised movie time only to find that they have to sit through several previews and preview ads before the movie starts. Many complain that the time devoted to previews is too long (The Wall Street Journal, October 12, 2012). A preliminary sample conducted by The Wall Street Journal showed that the standard deviation of the amount of time devoted to previews was 4 minutes. Use that as a planning value for the standard deviation in answering the following questions. Round your answer to next whole number,

a) If we want to estimate the population mean time for previews at movie theaters with a margin of error of 75 seconds, what sample size should be used? Assume 95% confidence.

b) If we want to estimate the population mean time for previews at movie theaters with a margin of error of 1 minute, what sample size should be used? Assume 95% confidence.

Answer:

a) the required Sample Size is 40

b) the required Sample Size is 62

Step-by-step explanation:

Given the data in the question;

standard deviation σ = 4 minutes

a)

margin of error E = 75 seconds = ( 75 / 60 )minutes = 1.25 minutes

And 95% confidence.

Now, Critical Value of z for 0.95 confidence interval;

∝ = 1 - 0.95 = 0.05

$Z_{\alpha /2$ = 1.96

so, sample size n will be;

n = [ $Z_{\alpha /2$ × σ/E ]²

we substitute;

n = [ 1.96 × (4/1.25) ]²

n = [ 1.96 × 3.2 ]²

n = [ 6.272 ]²

n = 39.338

Since we referring to a number of sample, its approximately becomes 40

Therefore, the required Sample Size is 40

b)

margin of error E = 1 minutes

And 95% confidence.

Now, Critical Value of z for 0.95 confidence interval;

∝ = 1 - 0.95 = 0.05

$Z_{\alpha /2$ = 1.96

so, sample size n will be;

n = [ $Z_{\alpha /2$ × σ/E ]²

we substitute;

n = [ 1.96 × (4/1) ]²

n = [ 1.96 × 4 ]²

n = [ 7.84 ]²

n = 61.466

Since we referring to a number of sample, its approximately becomes 62

Therefore, the required Sample Size is 62

6 0

1 year ago