Question

Stats Question:

A multiple-choice quiz has 15 questions, each with 4 possible answers of which only 1 is the correct answer.
What is the probability that sheer guesswork yields from 5 to 10 correct answers?
Please help me to solve this question with explanation.
Shami
Shami_Sweet@yahoo.com

Answer 1

@Shami Have you studied binomial probabilty?

Answer 2

Yes i did the same . I have solved many question but i am unable to understand this

Answer 3

Its like : nCx PxQ n-x

Answer 4

Then, when I write that the probability of getting *exactly 5 questions correct* by guessing is this:

P(5) = C(15,5) * (.25) ^5 * (.75) ^10 then do you get where those numbers come from?
@Shami

Answer 5

I think answers is 0.165145981

Answer 6

C (15, 5) means a combination of 15 questions taken 5 at the time and gives the number of ways groups of 5 questions can be selected from the 15 questions.

Answer 7

>>answers is 0.165145981 Answer to what? The entire question?

Answer 8

great dear.. i got

Answer 9

Not its answer is for P(X=5)

Answer 10

I am not interested in the answer at this point. I am interested in whether or not you know enough yet to follow how to do this problem after it we get it set up. Then, you can do the calculations.

So, if you just want the answer, then I can't help you because I don't know the answer but I do know how to find it.

Answer 11

Yes i dont need answers, i just to find out calculation of whole question

Answer 12

To do the problem, the individual probabilities for P(5), P(6), P(7), P(8), P(9), and P(10) will be calculated and then added to answer this question: What is the probability that sheer guesswork yields from 5 to 10 correct answers?

Answer 13

okay. i try to do it

Answer 14

P(5) = C(15,5) * (.25) ^5 * (.75) ^10 +
P(6) = C(15,6) * (.25) ^6 * (.75) ^ 9 +
P(7) = C(15,7) * (.25)^7 * (.75) ^ 8 +
P(8) = C(15,8) * (.25)^8 * (.75) ^ 7 +
P(9) = C(15,9) * (.25)^9 * (.75) ^ 6 +
P(10)=C(15,10) *(.25)^10 (.75) ^ 5 =

@Shami Crank out those numbers and add.
I'll do the same and we can compare, okay?

Answer 15

okay

Answer 16

my answer is 0.3133846

Answer 17

.31336 approx -- I truncated some decimals. I'd say that we have the same answer.

Answer 18

Check out the online binomial probability calculator at:
http://easycalculation.com/statistics/binomial-distribution.php

Answer 19

Thank you so much dear. M obliged really.

Answer 20

You are welcome.

Answer 21

Find the surface area of a square pyramid with a base that measures 10 m on each side and has a slant height of 20 m.

Answer 22

I got 400 as an answer. But it isn't one of my options. ):

Answer 23

2*10*15 + 10^2 this is what I did. and got 400.

Answer 24

2*10*20 + 10^2 = ?

The slant height is 20, not 15.

Answer 25

@dopegyal_ What did you get?

Answer 26

Oh wow... I need sleep . lol . 500 ?(:

Answer 27

Right. 500 is what I got.