# Math

If a grade was drawn at random from the data shown below, what is the probability that the grade is not a B?

A 2
B 8
C 11
D 2
F 1

I think it is 1 out of 5 or 4 but I am not sure? Please help :) Thank you much!

1. 👍 0
2. 👎 0
3. 👁 331
1. There are 5 possible outcomes, one of which is a B.
So what is P(B), and what is P(not B)?

Hint : P(B) and P(not B) have to add up to 1.

1. 👍 0
2. 👎 0
2. Oh ok I think I get it, so P(B)=0.5, 1/2,
and P(not B)=0.5,1/2???
Is that right?

1. 👍 0
2. 👎 0
3. Sorry, not really.

Figure out the probability of P(B) which is to get B out of 5 possible choices.

The rest would be easy to figure out.

1. 👍 0
2. 👎 0
4. Add up all the grades that aren't B's. Then put that over the total amount of grades.

1. 👍 0
2. 👎 0
5. Ok so it would be P(B)=0.8, the probability that the grade is not a B.?

I hope this is right now, if it isn't I give up....lol !

1. 👍 0
2. 👎 0
6. Don't give up, you're right.... almost!

What Jen showed you to do was
P(not B), which equals 0.8

there is only one grade B, so it is 1/5, there are 4 grades that are not B, so
P(not B)=4/5=0.8

Sorry if it was too confusing, hope it's more clear now.

1. 👍 0
2. 👎 0

## Similar Questions

1. ### math

two cards are selected at random without replacement from a well-shuffled deck of 52 playing cards. find the probability of the given event. a. two cards of the same suit are drawn. b. a pair is not drawn.

asked by Daren on April 25, 2014
2. ### Probability

Two cards are drawn at random from an ordinary deck of 52 playing cards. What is the probability of getting two faces if: a) the first card is replaced before the second card is drawn? b) the first card is not replaced before the

asked by Kenneth on July 20, 2020
3. ### math

a. A box contains three white balls and two red balls. A ball is drawn at random from the box and not replaced. Then a second ball is drawn from the box. Draw a tree diagram for this experiment and find the probability that the

asked by Anonymous on October 9, 2010
4. ### Math (Pease Help! 2 questions!)

A bag contains 2 white marbles and 7 purple marbles. Two marbles are drawn at random. One marble is drawn and not replaced. Then a second marble is drawn. c) What is the probability of selecting a purple marble and then a white

asked by Anonymous on January 28, 2016
1. ### Math (Statistics)

Determine whether a probability distribution is given. If a probability distribution is given, find its mean and standard deviation. If a probability distribution is not given, identify the requirements that are not satisfied. 8.

asked by Lexi on May 15, 2016
2. ### Math geometry

Please help , I only need the second part of the question Betty picks 4 random marbles from a bag containing 3 white , 4 yellow and 5 blue marbles The probability that exactly 1 of the 4 marbles drawn is blue is (0.3535) . The

asked by Katy on May 2, 2017
3. ### Math

A bag contains 2 white marbles and 7 purple marbles. Two marbles are drawn at random. One marble is drawn and not replaced. Then a second marble is drawn. A) What is the probability of selecting a purple marble and then a white

asked by Rima on April 13, 2015
4. ### math

Two cards are selected at random without replacement from a well-shuffled deck of 52 playing cards. Find the probability of the given event. (Round your answer to three decimal places.) find the probability that A pair is not

asked by Rico on November 8, 2011
1. ### math

A bag contains 12 red balls and 10 blue balls. A ball is drawn at random. The probability that ball drawn is red is

asked by fitsum on November 1, 2017
2. ### math

One card is selected at random from an ordinary set of 52 cards. Find the probability of each of the following events: b. A spade and a 5 are drawn. d. A jack is not drawn

asked by crystal on April 19, 2010
3. ### math

You roll a number cube numbered from 1 to 6. what is the probability you roll a number divisible by 4? Answer: I think 2/6 or 1/3 A number from 16 to 23 is drawn at random. what is the probability you draw a number greater than

asked by Anonymous on March 13, 2014
4. ### Math

Mr. Wong is a history teacher. In order to study how his 1st period class did on a 100-point test, he made the stem-and-leaf plot shown. Twenty-five students took the test. What conclusion can be drawn about the distribution of

asked by Connexus questioner on April 10, 2020