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andreev551 [17]
3 years ago
12

According to a recent survey, 50% of people aged 13 and older in the United States are addicted to texting. To simulate choosing

a random sample of 20 people in this population and seeing how many of them are addicted to texting, use a deck of cards. Shuffle the deck well, and then draw one card at a time. A red card means that person is addicted to texting; a black card means he isn’t. Continue until you have drawn 20 cards (without replacement) for the sample.
Mathematics
1 answer:
NeX [460]3 years ago
3 0

Answer:

It is not valid 49.02% instead of 50%

Step-by-step explanation:

If you don't replace the cards,the probability of obtaining a person that is addicted to email is no longer 50% after the first drawn card.

If you drawn a red card there are 25 red cards and 26 black cards then the probability of 25/25+26=25/51 ≅0.4902 = 49.02 instead of 50%

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What is the equation of the line with an x-intercept of -1 and a y-intercept of 2?
svlad2 [7]

Answer:

y = 2x + 2

Step-by-step explanation:

<em>(a) Slope </em>

The point-slope formula for a straight line is

y₂ - y₁ = m(x₂ - x₁)

The line goes through the points  (-1, 0) and (0, 2).

2 – 0 = m[0 – (-1)]

     2 = m

(b) y-intercept

y = mx + b

Use the point (0, 2)

     2 = 2× 0+ b

     2 = 0 + b

     b = 2

∴  y = 2x + 2

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Step-by-step explanation:

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Step-by-step explanation:

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IQ scores on the WAIS test approximate a normal curve with a mean of 100 and a standard deviation of 15. What IQ score is identi
riadik2000 [5.3K]

Answer:

IQ scores of at least 130.81 are identified with the upper 2%.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the z-score of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Mean of 100 and a standard deviation of 15.

This means that \mu = 100, \sigma = 15

What IQ score is identified with the upper 2%?

IQ scores of at least the 100 - 2 = 98th percentile, which is X when Z has a p-value of 0.98, so X when Z = 2.054.

Z = \frac{X - \mu}{\sigma}

2.054 = \frac{X - 100}{15}

X - 100 = 15*2.054

X = 130.81

IQ scores of at least 130.81 are identified with the upper 2%.

7 0
3 years ago
A quiz-show contestant is presented with two questions, question 1 and question 2, and she can choose which question to answer f
Mrrafil [7]

Answer:

The contestant should try and answer question 2 first to maximize the expected reward.

Step-by-step explanation:

Let the probability of getting question 1 right = P(A) = 0.60

Probability of not getting question 1 = P(A') = 1 - P(A) = 1 - 0.60 = 0.40

Let the probability of getting question 2 right be = P(B) = 0.80

Probability of not getting question 2 = P(B') = 1 - P(B) = 1 - 0.80 = 0.20

To obtain the better option using the expected value method.

E(X) = Σ xᵢpᵢ

where pᵢ = each probability.

xᵢ = cash reward for each probability.

There are two ways to go about this.

Approach 1

If the contestant attempts question 1 first.

The possible probabilities include

1) The contestant misses the question 1 and cannot answer question 2 = P(A') = 0.40; cash reward associated = $0

2) The contestant gets the question 1 and misses question 2 = P(A n B') = P(A) × P(B') = 0.6 × 0.2 = 0.12; cash reward associated with this probability = $200

3) The contestant gets the question 1 and gets the question 2 too = P(A n B) = P(A) × P(B) = 0.6 × 0.8 = 0.48; cash reward associated with this probability = $300

Expected reward for this approach

E(X) = (0.4×0) + (0.12×200) + (0.48×300) = $168

Approach 2

If the contestant attempts question 2 first.

The possible probabilities include

1) The contestant misses the question 2 and cannot answer question 1 = P(B') = 0.20; cash reward associated = $0

2) The contestant gets the question 2 and misses question 1 = P(A' n B) = P(A') × P(B) = 0.4 × 0.8 = 0.32; cash reward associated with this probability = $100

3) The contestant gets the question 2 and gets the question 1 too = P(A n B) = P(A) × P(B) = 0.6 × 0.8 = 0.48; cash reward associated with this probability = $300

Expected reward for this approach

E(X) = (0.2×0) + (0.32×100) + (0.48×300) = $176

Approach 2 is the better approach to follow as it has a higher expected reward.

The contestant should try and answer question 2 first to maximize the expected reward.

Hope this helps!!!

3 0
3 years ago
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