Questions on Normal Probability Models. Probability and area under the curve answered by real tutors!

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Question 1160354: Explain why a selection of 10 students from your class can have marks that are NOT normally distributed when the marks of the whole grade are normally distributed. The YouTube video that I posted in the “Content” area will assist you with this problem.
Click here to see answer by ikleyn(52786)

Question 1160696: A letter ticket has a grand prize of 35.1 million. The probability of winning the grand prize of .000000043. Determine the expected value of the lottery ticket?
Click here to see answer by ikleyn(52786)

Question 1160942: In order to qualify for a position, an applicant must score 86 or higher on a skills test.
If the test scores are normally distributed with a mean of 80 and a standard deviation
of 4, find the probability that a randomly selected applicant will qualify for the position.

Click here to see answer by Boreal(15235)

Question 1161365: Given the following table:
y | 15 30 60 90
p(y)| .2 .3 .4 .1
Find: Mean, Standard deviation, and probability that the time is within 1 SD of its mean.
Any help would be appreciated, thanks!
Click here to see answer by jim_thompson5910(35256)

Question 1161372: I appreciate any help I can get on this chance experiment problem. Please Help!
Jar of marbles initially contains 5 blue and 7 purple balls. Each time a marble is drawn, the color is noted and it is then replaced in jar urn along with 2 other balls of the same color (for example, John draws a blue marble on draw one, then places the blue marbles he selected along with two other blue marbles back in the jar).
a. What is the probability that the first 2 marbles drawn by John are blue and the next 2 are purple?
b. What is the probability that of the first 4 marbles drawn, exactly 2 are blue?

Click here to see answer by greenestamps(13200)

Question 1160943: If the average systolic blood pressure is 120 and the standard deviation is 10, find
the probability that a randomly selected person will have a blood pressure less than
108. Assume the variable is normally distributed.
Click here to see answer by Theo(13342)

Question 1162983: Two marksmen shoot at a target simultaneously. Shooter A is known to have a 70% chance
of hitting the target on any attempt. Person B has 40% accuracy. After the target is hit for the first time,
it is revealed that A shot 5 shots while B shot 12. What is the probability that it was A who hit the target?
What is the probability that person B hit the target? (Assume that accuracies of the shots remain the same
and are independent of other shots by either person.)
Click here to see answer by ikleyn(52786)

Question 1163018: if there is 7 red shirts on one team, and 5 more blue shirts of the red, but twice the blue shirts. find the red shirts
Click here to see answer by greenestamps(13200)

Question 1163206: 888.One stick is three times as long as another. You break the longer stick at a random point. Now you have three sticks. What is the probability that they form a triangle?
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Question 1163342: A coin with a 2-cm diameter is dropped onto a sheet of paper ruled by parallel lines that are 3 cm apart. Which is more likely, that the coin will land on a line, or that it will not?
Click here to see answer by ikleyn(52786)

Question 1167071: a marksman hits 75 of all his targets. what is the probability that he will exactly hit 4 of his next 10 shots
Click here to see answer by greenestamps(13200)

Question 1167073: in a survey concerning the use of three different brand of calculators, it was found that 55% use calculator a, 50% use calculator b, 40% use calculator c, 30% use calculator a and b, 20% use calculator a and c, 12% use calculator b and c and only 10% use all the three calculators. what percentages of the population do not use calculators
Click here to see answer by ikleyn(52786)

Question 1167072: 120 doctors surveyed, 60 are working in the academy, 50 are working in the industry, and 20 are working both in the academy and in the industry. if a doctor is chosen at random, find the probability that the doctor is working in either in an academy or in the industry
Click here to see answer by ikleyn(52786)

Question 1168630: Average Score = 88
Standard Deviation = 5
*Assuming that the scores were normally distributed:
Number of students who took test = 1250
--what percentage of students would have a score less than 80?
a. What is the z-score?
b. What is percentage?
MY ANSWER:
a.-1.60
b. 05.48 %
-hi can you check my answer if it is correct?
Click here to see answer by Boreal(15235)

Question 1169930: On an examination the average grade was 74 and the standard deviation was 7. If 12% of the class are given A's and 30% of the class given B's if the grades are curved to follow a normal distribution,
a)What is the lowest possible A's Marks.
b)What is the highest and lowest possible B's Marks.
Answers:
a)83 marks
b)82 and 75 marks.
Click here to see answer by Theo(13342)

Question 1170018: The marks for a university class were normally distributed with a mean of 65% and a standard deviation of 20%. What is the probability that a student selected at random from the class had a mark that was between 60% and 75%? Give your answer to four decimal places.
Click here to see answer by Boreal(15235)

Question 1170017: A teacher gave a test on which the students' marks were normally distributed, but the results were pathetic. The mean was 52%, and the standard deviation was 12%. The teacher decided that the top 10% of the students should get A's, the next 20% should get B's, the next 40% should get C's, the next 20% should get D's, and the bottom 10% should get F's. To the nearest percent, what was the minimum percent a student had to achieve in order to recieve a B? Do not include the percent sign in your answer.
Click here to see answer by Theo(13342)

Question 1170556: The area under the normal curve between μ- 3.5σ and μ+ 1.0σ is
Answer:0.8411
Click here to see answer by Boreal(15235)

Question 1171242: You have 12 different video games. How many different ways can you arrange the games side by side on a shelf?
You can arrange the 12 different video games in
nothing different ways.
Click here to see answer by Solver92311(821)

Question 1171753: You were told that the amount of time elapsed between consecutive trades on a foreign stock exchange market followed a normal distribution with a mean of 15 seconds. You were also told that the probability that the time elapsed between two consecutive trades would fall below 13 seconds was 13%. The probability that the time elapsed between two consecutive trades would fall below 13 seconds was 7%. What is the probability that the time elapsed between two consecutive trades will be between 14 and 17 seconds?
Click here to see answer by Solver92311(821)

Question 1172465: The mean life of stockings used by an army was 40 days with SD of 8 days. Assume the life of stockings follows normal distribution. If 100000 pairs are issued, how many would need replacement (i) before 24 days (ii) after 56 days?
Click here to see answer by Boreal(15235)

Question 1172479: The heights of applicants to the police force are normally distributed with mean 170 cm and standard deviation 3.8 cm. If 30% applicants are rejected on account of their low height. What is the minimum acceptable height for the police force?
Click here to see answer by Theo(13342)

Question 1172478: The heights of applicants to the police force are normally distributed with mean 170 cm and standard deviation 3.8 cm. If 30% applicants are rejected on account of their low height. What is the minimum acceptable height for the police force?
Click here to see answer by Boreal(15235)

Question 1172896: A phone company keeps statistics on the number of messages text that your customers send each month. According to statistics, the number of messages sent per customer in a month has a normal distribution. The data is shown below.
• The average is 278 messages per month.
• The standard deviation is 19 messages per month.
What is the probability that a customer sends LESS than 316 messages in a month?
Click here to see answer by Boreal(15235)

Question 1173518: Find the z-score that corresponds to the following areas.
Area to the left is 1.24

Click here to see answer by Theo(13342)

Question 1174512: In a certain communications system, there is an average of 1 transmission error per 10 seconds Let the distribution of transmission errors, say X be a Poisson distribution. What is the probe ability of more than 1 error in a communication half minute in duration?
Click here to see answer by Boreal(15235)

Question 1174777: Among 200 patients at a Tikur Anbessa hospital.
Click here to see answer by ikleyn(52786)

Question 1177087: In a survey of 250 Voters prior to the election, 16% indicated that they would vote for the ABC candidate. Estimate with 90% confidence the population proportion of voters who support the ABC.
Click here to see answer by Boreal(15235)

Question 1177853: If a golfer tees off 50 times on 10,000 square foot course how many times (what is the probability) that he will land on the 1,200 foot green that lies within that 10,000 foot course. :a probability & area question
Click here to see answer by ikleyn(52786)

Question 1178343: The weights of a certain group of high school boys have a normal distribution with a mean of 146 lb and a standard deviation of 10lb. Find the percent of the group having a weight
(a) greater than 154 lb.
(b) less than 132 lb.
Click here to see answer by Boreal(15235)

Question 1179065: At a local high school, GPA's are normally distributed with a mean of 2.9 and standard deviation of 0.6. What is the GPA of the highest 2.5% of the students?
Click here to see answer by ewatrrr(24785)

Question 1179519: A man gets a raise of 12% in salary at end of first year and further raises of 16% ,19% and 25% at the end of second, third and fourth years respectively; the raise in each year being calculated on his salary at the beginning of the year. What is the average annual percentage increase?

Click here to see answer by greenestamps(13200)

Question 1179759: In Statistics and Probability examination, the average grade was 74 and the standard deviation was 7. If 11.9% of the class is given X’s scores, and the grades follow a normal distribution, what is the lowest possible score X and the highest possible score Y?

Click here to see answer by ewatrrr(24785)

Question 1181387: Doris is ranked at the first quartile in her senior class of 300 students. What is her rank in the class?
Click here to see answer by Boreal(15235)

Question 1182887: The percentage of the adult population in a large city that are women is 45%.
A court is to randomly select a jury of adults from the population of all adults in
this city. Find the probability that none of the 12 randomly selected adults
from this city is a woman.

1. Determine the binomial parameters, n and p, giving values and descriptions.
2. Determine the question being asked, P(x “=, <, <, >, or >” a number), that is, write the
question symbolically as illustrated in lecture videos (and page 2 of this lab 3 packet).
3. Determine the calculator command needed to solve the problem.
(See separate sheet on using calculator to solve binomial problems.)
4. Use the calculator to find the solution to the binomial probability;
round answers to 4 decimal places.
5. Write your answer in a sentence in terms of the application
Click here to see answer by greenestamps(13200)

Question 1183581: From actual road tests with the tires, Hankook Tires estimated that the mean tire mileage is 36,500 miles and that the standard deviation is 5000 miles. Data is normally distributed.
(i) What percentage of the tires can be expected to last more than 40,000 miles?
(ii) Assume that Hankook Tires is considering a guarantee that will provide a discount on replacement tires if the original tires do not provide the guaranteed mileage. What should the guarantee mileage be if the company wants no more than 10% of the tires to be eligible for the discount guarantee?

Click here to see answer by Theo(13342)

Question 1183741: For each of the following tobs values, determine the highest level of
significance associated with the decision taken.5
tobs df Decision
(i) 4.000 17 Reject Ha for a two-tailed test
(ii) 1.200 120 Reject Ha for a one-tailed test
(iii) -2.660 16 Reject Ha for both one-tailed
and two-tailed test
(iv) -1.586 60 Reject Ha for a one-tailed test
Click here to see answer by MathLover1(20850)

Question 1184449: please help me with this question, it would be highly appreciated:
3 tiles with the letter X on them and 3 tiles with the letter O on them are placed in a row. The order is chosen at random. What is the probability that no two adjacent tiles have the same letter on them?
Thank you taking time out of your day to help me!

Click here to see answer by ikleyn(52786)

Question 1185582: 2. The medical Rehabilitation Education Foundation reports that the average cost of rehabilitation forstroke victims is $24,672. To see if the average cost of rehab is different at a particular hospital, a researcher selects a random sample of 35 stroke victims at the hospital and find the average cost of their rehab is $25,250. The standard deviation of the population is $3,251. At α= 0.01, can it be concluded that the average cost of stroke rehabilitation at the particular hospital is different from $24,672?a) State thenull and alternativehypotheses.b) Find the critical value from the appropriate table.c) Compute the test value.d) Make the decision to reject or not reject the null hypothesis.
Click here to see answer by Theo(13342)

Question 1186477: The waiting times between a subway departure schedule and the arrival of a passenger are uniformly distributed between 0 and 5 minutes. Fine the probability that a randomly selected passenger had a waiting time less than 2.75 minutes.
Click here to see answer by Edwin McCravy(20056)

Question 1188811: a school with 60 teachers is on alert during a nighttime
storm
to inform teachers whether the school will open the next day , the princeipal will call four teachers
each of whom will then call 2 others
and each of these will again call 2 others
so on untill all 60 have been contacted
how many people have to make 2 calls?
Click here to see answer by ikleyn(52786)

Question 1189095: A soft drink machine is regulated so that it discharges an average of 200 milliliters per cup. If the
amount of drink is normally distributed with a standard deviation equal to 15 millimeters, a) what fraction of the cups will contain more than 240 milliliters?
b) c) what is the probability that a cup contains between 191 and 209 milliliters? how many cups will likely overflow if 230 milliliters cups are used for the next 1000 di
d)
below what value do we get the smallest 25% of the drinks?

Click here to see answer by Boreal(15235)

Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270