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3 years ago

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A student is trying to calculate his semester average. He knows that his test average is an 80, his quiz average is a 72, homewo

rk is a 90, and classwork is a 93. If tests and quizzes are worth 30% each, and homework and classwork are worth 20% of his overall average, what is his average? Round to the nearest tenth.
What is the mean?

1 answer:

ELEN [110]3 years ago

4 0

You have to multiply and divide the 20% time the 30

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PLSSS HELP IF YOU TURLY KNOW THISSS

Nana76 [90]

Answer:

3

Step-by-step explanation:

Using the rule of exponents

$a^{m}$ ÷ $a^{n}$ = $a^{(m-n)}$ , then

$12^{6}$ ÷ $12^{3}$ = $12^{(6-3)}$ = 12³

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2 years ago

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Please help and answer

Lubov Fominskaja [6]

Answer:

so the answer is B,D,E,F

and question a is B i guess

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3 years ago

For a certain river, suppose the drought length Y is the number of consecutive time intervals in which the water supply remains

AnnZ [28]

Answer:

a) There is a 9% probability that a drought lasts exactly 3 intervals.

There is an 85.5% probability that a drought lasts at most 3 intervals.

b)There is a 14.5% probability that the length of a drought exceeds its mean value by at least one standard deviation

Step-by-step explanation:

The geometric distribution is the number of failures expected before you get a success in a series of Bernoulli trials.

It has the following probability density formula:

$f(x) = (1-p)^{x}p$

In which p is the probability of a success.

The mean of the geometric distribution is given by the following formula:

$\mu = \frac{1-p}{p}$

The standard deviation of the geometric distribution is given by the following formula:

$\sigma = \sqrt{\frac{1-p}{p^{2}}$

In this problem, we have that:

$p = 0.383$

So

$\mu = \frac{1-p}{p} = \frac{1-0.383}{0.383} = 1.61$

$\sigma = \sqrt{\frac{1-p}{p^{2}}} = \sqrt{\frac{1-0.383}{(0.383)^{2}}} = 2.05$

(a) What is the probability that a drought lasts exactly 3 intervals?

This is $f(3)$

$f(x) = (1-p)^{x}p$

$f(3) = (1-0.383)^{3}*(0.383)$

$f(3) = 0.09$

There is a 9% probability that a drought lasts exactly 3 intervals.

At most 3 intervals?

This is $P = f(0) + f(1) + f(2) + f(3)$

$f(x) = (1-p)^{x}p$

$f(0) = (1-0.383)^{0}*(0.383) = 0.383$

$f(1) = (1-0.383)^{1}*(0.383) = 0.236$

$f(2) = (1-0.383)^{2}*(0.383) = 0.146$

Previously in this exercise, we found that $f(3) = 0.09$

So

$P = f(0) + f(1) + f(2) + f(3) = 0.383 + 0.236 + 0.146 + 0.09 = 0.855$

There is an 85.5% probability that a drought lasts at most 3 intervals.

(b) What is the probability that the length of a drought exceeds its mean value by at least one standard deviation?

This is $P(X \geq \mu+\sigma) = P(X \geq 1.61 + 2.05) = P(X \geq 3.66) = P(X \geq 4)$ .

We are working with discrete data, so 3.66 is rounded up to 4.

Either a drought lasts at least four months, or it lasts at most thee. In a), we found that the probability that it lasts at most 3 months is 0.855. The sum of these probabilities is decimal 1. So:

$P(X \leq 3) + P(X \geq 4) = 1$

$0.855 + P(X \geq 4) = 1$

$P(X \geq 4) = 0.145$

There is a 14.5% probability that the length of a drought exceeds its mean value by at least one standard deviation

8 0

3 years ago

Write a polynomial function f of least degree that has a leading coefficient of 1 and the given zeros -4,-2,5. write the functio

OLga [1]

Answer:

Step-by-step explanation:

This is a third degree polynomial since we have 3 zeros. We find these zeros by factoring the given polynomial. The zeros of a polynomial are where the graph of the function goes through the x-axis (where y = 0). If x = -4, the factor that gives us this value is (x + 4) = 0 and solving that for x, we get x = -4. If x = -2, the factor that gives us that value is (x + 2) = 0 and solving that for x, we get x = -2. Same for the 5. The way we find the polynomial that gave us these zeros is to go backwards from the factors and FOIL them out. That means that we need to find the product of

(x + 4)(x + 2)(x - 5). Do the first 2 terms, then multiply in the third.

$(x+4)(x+2)=x^2+2x+4x+8$ , which simplifies to

$x^2+6x+8$

No we multiply in the final factor of (x - 5):

$(x^2+6x+8)(x-5)=x^3+6x^2+8x-5x^2-30x-40$ which simplifies to

$f(x)=x^3+x^2-22x-40$

If you are aware of the method for factoring higher degree polymomials, which is to use the Rational Root Theorem and synthetic division, you will see that this factors to x = -4, -2, 5. If you know how to use your calculator, you will find the same zeros in your solving polynomials function in your apps.

3 0

3 years ago

What is the surface area of the rectangular prism below?

Andrew [12]

Answer:

B ( 432 units^2)

Step-by-step explanation:

Total surface area= 2*(6*6)+ 4*(15*6)

There are 2 squares at each end of the same size so total area will be 2*(6*6)

If we look at the rectangles( bottom, top and the sides), we can see that all are of same dimensions and there are 4 of them so it's 4*(15*6)

In short, total surface area= 2*(6*6)+ 4*(15*6) = 432 units^2

5 0

3 years ago