Quiz has 6 questions. Each question has five possible answers,

only one of each 5 answers is correct.
If student randomly guesses on all six questions,
what is the probability to answer 2 questions right?

Tip: first, you have to define parameters of Binomial distribution:
n - how many trials/questions do you have
p - probability guessing right answer to each question
x - how many successes do you expect.
Then use Appendix Table or Excel function for Binomial distribution.
Answer

User Icon for MathMate MathMate answered
13 years ago

Assuming the 6 questions are independent,

n=6 (questions)
p=probability of guessing the right answer (1/5)
x=exactly the number of successes over the 6 questions (2).

Look up the appendix table, or the Excel function to calculate the probability.

Alternatively, use the formula:
P(x) = C(n,x)*px*(1-p)n-x
Where C(n,x) represents the number of combinations of taking n things, x at a time.

User Icon for Anonymous Anonymous answered
12 years ago

on a test midterm exam each multiple choice question provides five possible answers. what is the probability of randomly guessing three consecutive questions correctly?

User Icon for Anonymous Anonymous answered
11 years ago

.324

User Icon for Anonymous Anonymous answered
8 years ago

.24576

You're welcome

User Icon for abrham kussbilo abrham kussbilo answered
8 years ago

0.24576

User Icon for abrham kussbilo abrham kussbilo answered
8 years ago

answer 0.24576

User Icon for abrham kussbilo abrham kussbilo answered
8 years ago

p(x=4)=0.24576

User Icon for Xu Xu answered
7 years ago

p(x=4) = binompdf(6, 1/5, 4) = 0.2458

User Icon for Peter Peter answered
2 years ago

Good

User Icon for Explain Bot Explain Bot answered
11 months ago

To calculate the probability of answering 2 questions right out of 6, we can use the binomial distribution formula:

P(x) = (nCx) * (p^x) * ((1-p)^(n-x))

Where:
- P(x) is the probability of getting exactly x successes
- n is the number of trials/questions (which is 6 in this case)
- p is the probability of guessing the right answer for each question (which is 1/5 or 0.2 in this case)
- x is the number of successes we want (which is 2 in this case)

Using this formula, we can calculate the probability as follows:

P(2) = (6C2) * (0.2^2) * (0.8^(6-2))

Let's break it down step by step:

1. Calculate the number of combinations: (6C2) = 6! / (2! * (6-2)!) = 15

2. Raise the probability of guessing right (0.2) to the power of the number of successes we want (2): (0.2^2) = 0.04

3. Raise the probability of guessing wrong (0.8) to the power of the number of failures (6-2): (0.8^4) = 0.4096

4. Multiply all the values together: P(2) = 15 * 0.04 * 0.4096 = 0.24576

Therefore, the probability of answering 2 questions right out of 6, when guessing randomly, is approximately 0.24576 or 24.576%.