Amultiple choice test consists of 7 questions. each question has answer choices of a,b,c, and d, and only one of the choices is correct. if a student randomly guesses on each question, what is the probability that he gets at most 2 of them correct?

A multiple-choice test consists of 9 questions. Each question has answer choices of a, b, c, d, and e, and only one of the choices is correct. If a student randomly guesses on each question, what is the probability that she gets fewer than 2 of them correct?

Binomial Problem with n = 9 and p(correct) = 1/5
Hope this helps!
Answer n= 9 and p(correct)= 1/5

0.7564

Step-by-step explanation:

Since, we know that in this case, P(correct) is 1/4 because we have four options i.e. a, b, c, and d and number of mcqs 'n' is 7. So, we can use this permutations formula:

P(0 <= x <= 1) = binomcdf(7,1/4,2) = 0.7564

Hence, the probability of getting atleast 2 of them correct is 0.7564.

t = 15825.11 years

Step-by-step explanation:

From the given information:

We can make use of the activity of the sample present after time "t" to determine the age of the sample.

This can be expressed by the formula:

--- (1)

where;

= activity of the sample at time t = 0

= disintegration constant

If we replace the value of  into equation (1), we have:

By rearrangement:

t = 15825.11 years