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2 years ago

Need help on 5 & 6 please !!!

Mathematics

1 answer:

Novosadov [1.4K]2 years ago

5 0

Step-by-step explanation:

Q5. Let the cost of 28subscriptions be $s.

Words: 1subscription/28subscription = $21/$28

Numbers: 1/28 = 21/s

Cross multiply and solve: 1 x s = 21 x 28

s = 588

Answer with label: $588

Q6.

Words: 2inches/3.6inches = 2.5hours/bhours

Numbers: 2/3.6 = 2.5/b

Cross multiply and solve:

2 x b = 2.5 x 3.6

2b = 9

b = 4.5

Answer with label: 4.5hours

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Kate bought 3 used CDs and 1 used DVD at the bookstore. Her friend Joel bought 2 used CDs and 2 used DVDs at the same store. If

natka813 [3]

Answer:

Cost of 1 DVD is $6.5

Cost of one CD is $4.5

Combine cost of one DVD and CD is $11

Step-by-step explanation:

Given :

Kate bought 3 used CDs and 1 used DVD at the bookstore.

Her friend Joel bought 2 used CDs and 2 used DVDs at the same store.

Kate spent $20

Joel spent $22

To Find : the cost of a used CD and a used DVD

Solution :

Let cost of 1 used CDs be $x

Let cost of 1 used DVDs be $y

Cost of 3 used CDs = $3x

Cost of 2 used CDs = $2x

Cost of 2 used DVDs = $2y

Kate bought 3 used CDs and 1 used DVD at the bookstore.

She spent $20

So, equation becomes :

⇒ $3x+y=20$ ---(a)

Joel bought 2 used CDs and 2 used DVDs. she spent $22.

So, equation becomes:

⇒ $2x+2y=22$ --(b)

Now solve (a) and (b) to determine the value of x and y

We will use substitution method

Substitute the value of x from (b) in (a)

$3(\frac{22-2y}{2} )+y=20$

$33-3y+y=20$

$33-2y=20$

$33-20=2y$

$13=2y$

$\frac{13}{2} =y$

$6.5 =y$

Thus cost of 1 DVD is $6.5

Now substitute this value of y in b to get value of x

⇒ $2x+2(6.5)=22$

⇒ $2x+13=22$

⇒ $2x=22-13$

⇒ $2x=9$

⇒ $x=\frac{9}{2}$

⇒ $x=4.5$

Thus the cost of one CD is $4.5

Hence the combine cost of one DVD and CD = $6.5+ $4.5=$11

6 0

3 years ago

I will give brainaliest if answer is correct.a baseball diamond is square.the distance from home plate to first base is 90 feet.

yan [13]

It would be 127 (usually a little over)

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3 years ago

Find the perimeter of the regular polygon 7x+4 5(x + 2) - 1

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Answer:

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2 years ago

Write 243 as a product of primes.

shtirl [24]

Answer:

243 = 3⁵

Step-by-step explanation:

Firstly we will find the factors of 243. On calculating it see that the factors of 243 are 3 x 3 x 3 x 3 x 3.

243 = 9 x 9 x 3

We need to write 243 as the product of primes.

The number that divides itself or 1 are prime numbers.

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Hence, this is the required solution.

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3 years ago

A researcher compares the effectiveness of two different instructional methods for teaching electronics. A sample of 138 student

yan [13]

Answer:

The 98% confidence interval for the true difference between testing averages for students using Method 1 and students using Method 2 is (-8.04, 0.84).

Step-by-step explanation:

The (1 - <em>α</em>)% confidence interval for the difference between population means is:

$CI=(\bar x_{1}-\bar x_{2})\pm z_{\alpha/2}\times \sqrt{\frac{\sigma^{2}_{1}}{n_{1}}+\frac{\sigma^{2}_{2}}{n_{2}}}$

The information provided is as follows:

$n_{1}= 138\\n_{2}=156\\\bar x_{1}=61\\\bar x_{2}=64.6\\\sigma_{1}=18.53\\\sigma_{2}=13.43$

The critical value of <em>z</em> for 98% confidence level is,

$z_{\alpha/2}=z_{0.02/2}=2.326$

Compute the 98% confidence interval for the true difference between testing averages for students using Method 1 and students using Method 2 as follows:

$CI=(\bar x_{1}-\bar x_{2})\pm z_{\alpha/2}\times \sqrt{\frac{\sigma^{2}_{1}}{n_{1}}+\frac{\sigma^{2}_{2}}{n_{2}}}$

$=(61-64.6)\pm 2.326\times\sqrt{\frac{(18.53)^{2}}{138}+\frac{(13.43)^{2}}{156}}\\\\=-3.6\pm 4.4404\\\\=(-8.0404, 0.8404)\\\\\approx (-8.04, 0.84)$

Thus, the 98% confidence interval for the true difference between testing averages for students using Method 1 and students using Method 2 is (-8.04, 0.84).

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3 years ago