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2 years ago

What's the answer to number 7

Mathematics

2 answers:

Law Incorporation [45]2 years ago

8 0

Ginny is correct. Five quarters makes it $1.25 plus three dimes which is $.30 makes it $1.55

Savatey [412]2 years ago

5 0

No, she is not correct, because there has to be 11 coins, and there is only 8.

The correct answer is 8 dimes and 3 quarters, because those equal 1.55 :)
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Find two positive numbers satisfying the given requirements. The product is 432 and the sum of the first plus three times the se

kogti [31]

Answer:

Step-by-step explanation:

Let the two positive integers be x and y.

If their product is 432, then

xy = 432 ......... 1

Also if the sum of the first plus three times the second is a minimum, then;

p(x) = x + 3y

From 1;

y = 432/x ..... 3

Substitute 3 into 2;

p(x) = x+3y

p(x)= x + 3(432/x)

p(x) = x + 1296/x

Since the expression is at minimum when dp(x)/dx = 0

dp/dx = 1 + (-1296)/x²

dp/dx = 1 -1296/x²

0 = 1 -1296/x²

0 = (x²-1296)/x²

cross multiply

0 = x²-1296

x² = 1296

x = √1296

x = 36

Since xy = 432

36y = 432

y = 432/36

y = 12

Hence the two positive numbers are 36 and 12

4 0

2 years ago

Most dermatologists recommend using sunscreens that have a Sun Protection Factor (SPF) of at least 30. One of the authors wanted

Basile [38]

Answer: We are 95% confident that the mean SPF level of sunscreen used by all Cal Poly students is between 29.0813 and 40.0187.

Step-by-step explanation:

Given : Significance level : $\alpha: 1-0.95=0.05$

Sample size : n= 52 , which is a large sample (n>30), so we use z-test.

By using z-value table,

Critical value: $z_{\alpha/2}=1.96$

Sample mean : $\overline{x}= 34.55$

Standard deviation : $\sigma= 20.12$

The confidence interval for population means is given by :-

$\overline{x}\pm z_{\alpha/2}\dfrac{\sigma}{\sqrt{n}}$

i.e. $34.55\pm(1.96)\dfrac{ 20.12}{\sqrt{52}}$

$=34.55\pm5.46867829455\\\\\approx34.55\pm5.4687\\\\=(34.55-5.4687, 34.55+5.4687)=(29.0813,\ 40.0187)$

Now, the 95% confidence interval for the ppopulation mean = . (29.0813, 40.0187)

Hence, We are 95% confident that the mean SPF level of sunscreen used by all Cal Poly students is between 29.0813 and 40.0187.

7 0

3 years ago

in the equation y equals 8X y is the dependent variable and X is the independent variable what happens to the dependent variable

goblinko [34]

As the independant variable increases, the dependant variable increases at a constant rate creating a linear relationship.

4 0

3 years ago

Someone please help I’ve been spamming on this and no one has helped yet so please

Gre4nikov [31]

Answer:

The value of x would 12.2.

Step-by-step explanation:

You have to use the pythagorean theorem to solve this.

a = 5.85 (11.7/2)

b = what we are trying to find

c = 13.5

$\sqrt{13.5^{2} - 5.85^{2} }$ = 12.1666 which rounds to 12.2

I hope this helps, I apologize if it isn't right.

3 0

2 years ago

How many hours did it take him to finish the project?

EleoNora [17]

First, find 20% of 5 hours. 20% is also 1/5 of something, and 1/5 of 5 is 1.
Multiply 5 by 3 for the 300%, getting 15 hours, and add 1 for the 20%.
He spent 16 hours on the project. Hope this helps!

8 0

3 years ago