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Reika [66]
3 years ago
9

Yi is running for class president. To try to predict how people will vote, she wants to take a poll with a 90% confidence level

(z*-score of 1.645) and an estimated margin of error of 4%. What is the approximate minimum sample size for Yi’s initial poll?
Mathematics
2 answers:
slega [8]3 years ago
8 0
90The information that you'd need in determining sample size when the standard deviation is unknown is:

z-value for the given level of confidence ⇒ The level of confidence is 90% and the z-value by convention is 1.645

The margin error (E) = 4%

The proportion of the population that you'd expect to vote for Yi. If this information isn't provided, use 50%. We call this value, p, the probability of success.

The probability of not success is q = 1 - 0.5 = 0.5

STEP 1:
Half the margin error = 0.04 ÷ 2 = 0.02

STEP 2:
Multiply the probability of success by the probability of fail = 0.5 × 0.5 = 0.25

STEP 3: 
Divide z-score by half of E = 1.645 ÷ 0.02 = 82.25
Then square the answer = 82.25² = 6765 rounded to the nearest integer)

STEP 4: 
Multiply the answer from STEP 2 by the answer from STEP 4
0.25 × 6765 = 1691 (rounded to the nearest integer)

Answer: Minimum Sample Size is 1691
Savatey [412]3 years ago
5 0

Answer:

D. 1,692 students

Step-by-step explanation:

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3 years ago
A blind man wanders under a door into an empty room. After running into the walls repeatedly for a while, it stops to think and
Nostrana [21]

From the side where the man is located in the 10' by 12' rectangular room, we have;

A) 0.046

B) The average time to escape in first attempt is approximately 605.02 seconds

<h3>Which concept can be used to find the odds and time of escape?</h3>

A) From The given diagram, we have;

Width of the door = 10 - 6 - 2 = 2

Therefore, the door is 2 feet wide

Distance, d1, from the man to the side of the door closer to him is given by Pythagorean theorem as follows;

  • d1 = √(6² + 7²) = √(85)

From the furthest side of the door to the man, we have;

  • d2 = √(7² + 8²) = √(113)

According to the law of cosines, we have;

2² = 85+113 - 2×√(85)×√(113) cos(A)

Where angle <em>A </em>is the angle formed by the lines from the man to the closer and farther sides of the door.

2×√(85)×√(113) cos(A) = 85+113 - 2²

A = arccos((85+113 - 2²)/(2×√(85)×√(113)))

A = arccos (194/(2×√(9605)) ≈ 8.213°

The angle of the possible directions in which the man can turn is 180°.

Therefore;

The probability, <em>P(</em><em>E)</em>, of escaping in the first move is therefore;

  • P(E) = 8.213°/180° ≈ 0.046

B) Given that the man escapes in the first move, the shortest and longest distances the man moves are;

d1 = √(85) and d2 = √(113)

Speed of the man, <em>v </em>= 0.5 cm/sec

Therefore by unit conversion function of a graphing calculator;

  • v = (25/1524) ft./sec

The times taken are;

t1 = √(85)/(25/1524) ≈ 562.023

t2 = √(113)/(25/1524) ≈ 648.014.

Average time, <em>t </em>= (t1 + t2)/2

Which gives;

t = (562.023 + 648.014)/2 ≈ 605.02

The average time it takes the man to escape in first move is <em>t </em><em>≈</em> 605.02 seconds.

Learn more about Pythagorean theorem and probability here:

brainly.com/question/27180985

brainly.com/question/654982

brainly.com/question/24756209

#SPJ1

3 0
1 year ago
Dr.Wong can see 11 patients in 2 hours . At this rate ,how long would it take her to see 88 patients
melamori03 [73]

88 divided by 11 = 8

8 x 2 = 16

16hrs

3 0
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