1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
bezimeni [28]
3 years ago
7

Suppose that in one of your classes you are given 20 questions, and are told that the final exam will consist of 8 of them. Supp

ose that the 8 that are chosen for the final are selected randomly.
a) If you work out how to do 12 of the problems, what is the probability that you will be able to work at least 7 of those on the final?

b) How many problems do you need to have worked out to have a 90% probability of being able to solve all 8 of those on the final?
Mathematics
1 answer:
Misha Larkins [42]3 years ago
6 0

Answer:

a) The probability is 0.054227. You are going to be able to answer 7 questions 5.42% of the time

b) You need to be able to answer all 20 quesitons for at least a 90% chance.

Step-by-step explanation:

a) We can calculate this probability by dividing the total amount of favourable cases with the total amount of cases (because all possible exams of 8 questions are equally probable).

From 12 questions we work out on and 8 we didnt, we will be fine is at least 7 questions from the 8 given are the ones that we worked out.

The total amount of exams with exactly 7 questions we can answer is

{12 \choose 7} * 8 = 6336

First we pick 7 from 12, and then we pick 1 of the 8 questions we dont know the answer.

The total amount of exams with 8 questions we know the answer is the total amount of ways to pick 8 form 12, thus it is {12 \choose 8} = 495 . Therefore, there are a total of 6336+495 = 6831 favourable cases.

The total amount of exams, on the other hand, is the total amount of ways to pick 8 from 20, therefore it is {20 \choose 8} = 125970 .

The probability to get 7 questions we work out to do is 6831/125970 = 0.054227. Thus, we are going to be fine only 5.42% of the time.

b) Combinatorial numbers grows pretty quickly. If we were to solve 19 out of 20 problems, then the probability of getting all 8 problems is

19/20 * 18/19 * 17/18 * 16/17 * 15/16 * 14/15 * 13/14 * 12/13 = 12/20 = 0.6

(for the first question of the exam, 19 out of 20 are fine, for the second question, of the 19 questions remaining, 18 can be answered, and so on)

This means that, if you want a 90% chance of answering all 8 questions, you need indeed be able to answer all 20 questions provided you are given.

You might be interested in
A total of 70 tickets were sold for a concert and earn the organizers $804. If the cost of each ticket is either $10 or $12, how
crimeas [40]

Answer:

52 tickets cost $10 and 18 tickets cost $12

Step-by-step explanation:

10x+12y=804. (1)

x+y=70. (2)

From (2)

x=70-y

Substitute x=70-y into (1)

10x+12y=804

10(70-y)+12y=804

700-10y+12y=804

700+2y=804

2y=804-700

2y=104

y=104/2

y=52

Recall

x+y=70

x+52=70

x=70-52

x=18

52 tickets cost $10 and 18 tickets cost $12

5 0
3 years ago
Use the graph of the quadratic function y = - 1x2 + x + 4 to
True [87]

Answer: A, -2 and 4

Step-by-step explanation: cause it it you’re welcome

6 0
3 years ago
Explain the process for finding the product of 2 integers
crimeas [40]
Product means to multiply. Integers are whole numbers, so the process would be to multiply the numbers.
3 0
3 years ago
Question
mixer [17]

The intervals are given as follows:

  • In range notation: [-282, 20,320].
  • In set-builder notation: {x|x ∈ ℝ, -282 <= x <= 20,320}

<h3>What is the range of elements notation for interval?</h3>

The range of elements notation for interval is given by:

[a,b].

In which:

  • a is the smallest value.
  • b is the greatest value.

In this problem these values are given by:

a = -282, b = 20,320.

Hence the interval in range notation is given by:

[-282, 20,320].

<h3>How to write the interval in set-builder notation?</h3>

The same interval can be written as follows, using set-builder notation?

{x|x ∈ ℝ, a <= x <= b}

Hence, for the situation described in this problem, the set-builder notation for the values is:

{x|x ∈ ℝ, -282 <= x <= 20,320}

More can be learned about notation of intervals at brainly.com/question/27896097

#SPJ1

5 0
2 years ago
The weather report states that the probability it will rain on Wednesday is 30 percent and the probability that it will rain on
Sauron [17]
Since these 2 events are independent , the probability of them both occurring is obtained by multiplying them

P(rain on Wed and Sat) =0.30* 0.60 = 0.18

 which is 18%
3 0
2 years ago
Read 2 more answers
Other questions:
  • There are 2 orange picks for every 5 picks if there are 21 picks in total how many picks are orange
    15·1 answer
  • What is the reason for using greatest common factor?
    9·2 answers
  • 218 rounded to nearest 10
    11·2 answers
  • -5(3)(2)=?<br><br> show how you got the answer
    15·2 answers
  • Kenji is playing the video game dragon tamer, where players go on a adventure finding and training. In the first level he gets 1
    8·1 answer
  • Jaleesa bought a movie online. She paid $19.00 plus tax. The sales tax was 9%. How much did she pay in sales tax?
    7·1 answer
  • What multiplies to be -18 and adds to be -9?
    8·1 answer
  • What is:<br> 3/4 / 1/4<br> -4/5 / 8/9 <br> -5/6 / (-2/3)
    9·1 answer
  • Find the measure of one interior angle for the following regular polygon
    13·1 answer
  • PLEASEEE HURRY<br><br> Please please please
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!