Question

The probability of failure in physics practical examination is 20% . If 25 batches of 6 students each take the examination, in how many batches 4 or more students would pass

Answer 1

Total students = 25 x 6 = 150

Students who will fail = 0.2 x 150 = 30

Students who will fail per batch = 0.2 x 6 = 1.2 which is not an integer, hence, in some batches two students will fail and in some batches 1 will fail

30 = 2n1 + n2

n1 + n2 = 25

n1 =5 n2 = 20..20 is the answer.

Please mark brainliest if answer is correct

Answer 2

Using bionomial distribution:

Total number of students is 6.

Out of which we want 4 or more i.e 4,5,6 passed students.

Probability of 4 or more students passing is as follows:

6C4×0.2^2×.8^4 + 6C5×0.2^1×0.8^5+6C6×0.2^0×0.8^6

= 0.902.

If there are 25 batches then let's find out in how many batches more than 4 students passed by multiplying the probability with number of batches time 25.

:. no. of batches × probability of 4 or more passed students.

= 25× 0.902 = 23 (rounded up)