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
klio [65]
3 years ago
14

On a multiple choice test with 15 ​questions, each question has four possible​ answers, one of which is correct. For students wh

o guess at all​ answers, find the variance for the number of correct answers. Round to the nearest tenth.
Mathematics
1 answer:
Aleks [24]3 years ago
5 0

Answer:

The variance for the number of correct answers is 2.8 questions

Step-by-step explanation:

The number of correct answers follows binomial distribution, in which we have:

  • n identical and independents events: the 15 questions
  • two possibles results that we call success and fail: The answer is correct and the answer is incorrect
  • probability p of success and 1-p of fail. Probability 1/4 of get the answer correct and probability of 3/4 of get the answer incorrect. This probabilities are calculated on that way because every question have 4 possible answers and one of which is correct.

So, the variance for a variable x that follows a Binomial distributions is:

V(x)=n*p*(1-p)

Then, the variance for the number of correct answers is:

V(x)=15*(1/4)*(3/4) = 2.8125 ≈ 2.8

Because n is equal to 15, p is equal to 1/4 and (1-p) is equal to 3/4.

You might be interested in
Two parallel lines are cut by a transversal such that two alternate interior angles are formed. If one of the angles is 72 degre
levacccp [35]

Answer:

x=18

Step-by-step explanation:

5x+2=72

    -2  -2

5x=70

---------

  5

x=18

3 0
3 years ago
suppose you win a contest at the start of 9th grade that deposited $3000 in an account that pays 5% annual interest compound con
tiny-mole [99]
A=pe^rt
A=3,000×e^(0.05×8)
A=4,475.47
5 0
3 years ago
On a quiz, you answered 38 questions correctly out of 43. What percent did you answer correctly? (Round your answer to nearest p
horsena [70]

Answer:

D

Step-by-step explanation:

<u>38=x</u>

43=100

Cross multiply.

5 0
3 years ago
Read 2 more answers
Please help, I will give you brainliest!
V125BC [204]

Answer:

12 = 12 \\ 12 - 12 = 12 - 12 \\ 0 = 0

7 0
2 years ago
The question is there
Katarina [22]

Answer:

3 cm

Step-by-step explanation:

Set up an equation that solves for the surface area, "112cm^{2}" :

10(2)+10(2)+2x+2x+10x+10x = 112

20+20+4x+20x = 112

24x+40=112

24x=72

x=3

So, 3 cm.

7 0
3 years ago
Other questions:
  • A car salesman's total salary, (s) us a base salary plus a commission. The salesman has a base salary of $40,000 and receives a
    14·1 answer
  • Ari is painting blocks of wood for a project each block is 8 cm long 4cm wide and 5cm high what is the surface are of each block
    13·2 answers
  • The measure of Angle E, the angle of elevation from point A to point B, is ( 3 x plus 1 ). The measure of Angle D, the angle of
    5·1 answer
  • What is the slope of the line described by the equation below y=-6x+3
    13·2 answers
  • Say a certain service industry has 78.9 thousand jobs in 2003, but expects to increase at an average annual rate of 2.65 thousan
    7·2 answers
  • I need help with this question!! <br>Please Help!!
    13·1 answer
  • Suppose T: ℝ3→ℝ2 is a linear transformation. Let U and V be the vectors given below, and suppose that T(U) and T(V) are as given
    12·1 answer
  • Kate is going to the fair with three of her friends. It will cost $5.00 to get in and an additional $2 per ride. Create an equat
    5·1 answer
  • Which surveys would a sample be appropriate for? Mark all that apply.
    15·2 answers
  • Help please and thank you
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!