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3 years ago

11

Eva wants to buy a bicycle.The bicycle costs $240.Eva already has $42 saved.She babysits for $12 per hour.Eva needs to babysit f

or h hours to earn enough money to buy the bicycle.

1 answer:

dimulka [17.4K]3 years ago

3 0

Hi,

She lacks 240-42 = 198

She earns 12 usd per hours so : 198 /12 = 16.5

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A magazine article conducted a survey of 525 people in New York City and found that 30% of the population believe that the Yanke

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Answer:

In this case, the 30% represents the proportion of the sample. It is a statistic that can be used to estimate a parameter of the population.

Step-by-step explanation:

In this case, the 30% represents the proportion of this specific sample (survey taken by the magazine).

It is a statistic that can be used to estimate a parameter of the population. In this case, it may be used to estimate the true proportion of "people in New York who believe that the Yankees will miss the playoffs this year".

If a new sample is taken, a new statistic will be calculated that may or may not be equal to 30%.

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A mountain climber started at 150 feet below sea level. What would he

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3150 feet for both

Step-by-step explanation:

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2 years ago

When circuit boards used in the manufacture of compact disc players are tested, the long-run percentage of defectives is 5%. Let

sergiy2304 [10]

Answer:

(a) P(X=3) = 0.093

(b) P(X≤3) = 0.966

(c) P(X≥4) = 0.034

(d) P(1≤X≤3) = 0.688

(e) The probability that none of the 25 boards is defective is 0.277.

(f) The expected value and standard deviation of X is 1.25 and 1.089 respectively.

Step-by-step explanation:

We are given that when circuit boards used in the manufacture of compact disc players are tested, the long-run percentage of defectives is 5%.

Let X = <em>the number of defective boards in a random sample of size, n = 25</em>

So, X ∼ Bin(25,0.05)

The probability distribution for the binomial distribution is given by;

$P(X=r)= \binom{n}{r} \times p^{r}\times (1-p)^{n-r} ; x = 0,1,2,......$

where, n = number of trials (samples) taken = 25

r = number of success

p = probability of success which in our question is percentage

of defectivs, i.e. 5%

(a) P(X = 3) = $\binom{25}{3} \times 0.05^{3}\times (1-0.05)^{25-3}$

= $2300 \times 0.05^{3}\times 0.95^{22}$

= <u>0.093</u>

(b) P(X $\leq$ 3) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3)

= $\binom{25}{0} \times 0.05^{0}\times (1-0.05)^{25-0}+\binom{25}{1} \times 0.05^{1}\times (1-0.05)^{25-1}+\binom{25}{2} \times 0.05^{2}\times (1-0.05)^{25-2}+\binom{25}{3} \times 0.05^{3}\times (1-0.05)^{25-3}$

= $1 \times 1 \times 0.95^{25}+25 \times 0.05^{1}\times 0.95^{24}+300 \times 0.05^{2}\times 0.95^{23}+2300 \times 0.05^{3}\times 0.95^{22}$

= <u>0.966</u>

(c) P(X $\geq$ 4) = 1 - P(X < 4) = 1 - P(X $\leq$ 3)

= 1 - 0.966

= <u>0.034</u>

<u></u>

(d) P(1 ≤ X ≤ 3) = P(X = 1) + P(X = 2) + P(X = 3)

= $\binom{25}{1} \times 0.05^{1}\times (1-0.05)^{25-1}+\binom{25}{2} \times 0.05^{2}\times (1-0.05)^{25-2}+\binom{25}{3} \times 0.05^{3}\times (1-0.05)^{25-3}$

= $25 \times 0.05^{1}\times 0.95^{24}+300 \times 0.05^{2}\times 0.95^{23}+2300 \times 0.05^{3}\times 0.95^{22}$

= <u>0.688</u>

(e) The probability that none of the 25 boards is defective is given by = P(X = 0)

P(X = 0) = $\binom{25}{0} \times 0.05^{0}\times (1-0.05)^{25-0}$

= $1 \times 1\times 0.95^{25}$

= <u>0.277</u>

(f) The expected value of X is given by;

E(X) = $n \times p$

= $25 \times 0.05$ = 1.25

The standard deviation of X is given by;

S.D.(X) = $\sqrt{n \times p \times (1-p)}$

= $\sqrt{25 \times 0.05 \times (1-0.05)}$

= <u>1.089</u>

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The compliment of set A that is A' is equal to {2, 4, 8, 12, 16}.

We are given the universal set as:

U = {2, 4, 6, 8, 10, 12, 14, 16}

We are also given that set A is:

A = {6, 10, 14}

We need to find A'

For this, we will subtract set A from the universal set, U.

So, we get that:

A' = U - A

A' = {2, 4, 6, 8, 10, 12, 14, 16} - {6, 10, 14}

Solving the expression, we get that:

A' = {2, 4, 8, 12, 16}

Therefore, we get that, the compliment of set A that is A' is equal to {2, 4, 8, 12, 16}.

Learn more about sets here:

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3 years ago