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2 years ago

Write a proportion to find how many points x a student needs to score on a test worth 50 points to get a test score of 78%.

1 answer:

4 0

The answer is: "39 points" .
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Explanation:
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" x/ 50 = 78/100 " ; in which "x" equals the number of points needed.

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To solve for "x" ;
_______________________________________________________

Look at the denominators: 50 * (what value?) = 100.

→ "100 ÷ 50 = 2" .

→ So; "50 * 2 = 100" ;

So, let us look at the numerators:

x * 2 = 78 ;

↔ 2x = 72 ;

Divide each side of the equation by "2" ; to isolate "x" on one side of the equation ; and to solve for "x" ;
_____________________________________________
→ 78 ÷ 2 = 39 ;

The answer is: "39 points" .
_____________________________________________

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A random variableX= {0, 1, 2, 3, ...} has cumulative distribution function.a) Calculate the probability that 3 ≤X≤ 5.b) Find the

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Answer:

a) P ( 3 ≤X≤ 5 ) = 0.02619

b) E(X) = 1

Step-by-step explanation:

Given:

- The CDF of a random variable X = { 0 , 1 , 2 , 3 , .... } is given as:

$F(X) = P ( X =< x) = 1 - \frac{1}{(x+1)*(x+2)}$

Find:

a.Calculate the probability that 3 ≤X≤ 5

b) Find the expected value of X, E(X), using the fact that. (Hint: You will have to evaluate an infinite sum, but that will be easy to do if you notice that

Solution:

- The CDF gives the probability of (X < x) for any value of x. So to compute the P ( 3 ≤X≤ 5 ) we will set the limits.

$F(X) = P ( 3=$

- The Expected Value can be determined by sum to infinity of CDF:

E(X) = Σ ( 1 - F(X) )

$E(X) = \frac{1}{(x+1)*(x+2)} = \frac{1}{(x+1)} - \frac{1}{(x+2)} \\\\= \frac{1}{(1)} - \frac{1}{(2)}\\\\= \frac{1}{(2)} - \frac{1}{(3)} \\\\= \frac{1}{(3)} - \frac{1}{(4)}\\\\= ............................................\\\\= \frac{1}{(n)} - \frac{1}{(n+1)}\\\\= \frac{1}{(n+1)} - \frac{1}{(n+ 2)}$

E(X) = Limit n->∞ [1 - 1 / ( n + 2 ) ]

E(X) = 1

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2 years ago

Steven's family traveled 7/10 of the distance to his aunt’s house on Saturday. They traveled 2/3 of the remaining distance on Su

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Answer:

Step-by-step explanation:

Answer: 1/5 of the total distance to his grandmothers house was traveled on Sunday

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1 - 7/10 = 3 /10

They traveled 2/3 of the remaining distance on Sunday. This means that the distance that they travelled on Sunday is

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1 year ago

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Step-by-step explanation:

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2 years ago

The pyramid of khagra,in Egypt,is 488 feet tall. The Eiffel Tower,in France,is 1,063 feet tall. How much taller is the Eiffel To

steposvetlana [31]

Answer:

The Eiffel Tower in France is 575 feet taller than pyramid of khagra.

Step-by-step explanation:

We are given the following in the question:

Height of pyramid of khagra = 488 feet

Height of Eiffel Tower in France = 1,063 feet

Difference in height =

= Height of Eiffel Tower in France - Height of pyramid of khagra

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Thus, the Eiffel Tower in France is 575 feet taller than pyramid of khagra.

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2 years ago

Several years ago, 50% of parents who had children in grades K-12 were satisfied with the quality of education the students r

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Answer:

The 95% confidence interval for the proportion of parents that are satisfied with their children's education is (0.4118, 0.4618). 0.5 is not part of the confidence interval, so this represents evidence that parents' attitudes toward the quality of education have changed.

Step-by-step explanation:

We have to see if 50% = 0.5 is part of the confidence interval.

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.