Measures of Central Tendency 2

1. In a poll, respondents were asked whether they had ever been in a car accident. 177 respondents indicated that they had been in a car accident and 107 respondents said that they had not been in a car accident. If one of these respondents is randomly selected, what is the probability of getting someone who has been in a car accident?

Total number of sample or population of respondents

=107+177=284

Probability someone was in an accident=n/N

Where n=part of the population involved in accident

And N= the entire population or sample size

177/284=0.62

2. The data set represents the income levels of the members of a country club. Find the probability that a randomly selected member earns at least $102,000  INCOME (Thousands of dollars) 108   128     82   138    85   108    88    76   158   208   79     98   148    85   128   118    88   168    73   118

For this problem we arrange the data in ascending order as follows

73,76,79,82,85,85,88,88,98,108,108,118,118,128,138,148, 158,168, 208

From this point we determine our n and N as defined above

N is the total number of population or sample while n is the number of occurrences in the total outcomes we are interested in.

N=20, n=11

Probability to get over 102,000 salary for the members=

11/20=0.55

3. In a certain class of students, there are 13 boys from Wilmette, 3 girls from Kenilworth, 11 girls from Wilmette, 6 boys from Glencoe, 5 boys from Kenilworth and 6 girls from Glencoe. If the teacher calls upon a student to answer a question, what is the probability that the student will be from Kenilworth?

Wilmette Kenilworth Glencoe total

Boy 13 5 6 24

Girls 11 3 6 20

Total student population=44

Total from kenilworth=8

Probability =8/44=0.18

4. Find the probability of correctly answering the first 2 questions on a multiple choice test if random guesses are made and each question has 4 possible answers.

Total answers =8

The first two answers=2

Probability =2/8=0.25

5. Of 1906 people who came into a blood bank to give blood, 300 people had high blood pressure. Estimate the probability that the next person who comes in to give blood will have high blood pressure.

Total number=1906

Those with blood pressure=300

Probability=300/1906=0.15