Some students appeared for a physiological exam in which each question had 4 choices . The student , who will give all the answers correctly , will be declared passed .
If all students answerd differently and oot of all students , 255 failed , then the total number of questions in the test was
A . 3
B . 4
C . 5
D . 6
Answers
Answered by
1
Answer:
4is a answer............
Answered by
3
Answer:
B . 4
255 students failed. Since all students answered differently only one student answered all the questions correctly. Hence only one student passed. Hence there were 256 students. This indirectly means that there are 256 ways to give answers to the test.
There are 4 options. So one can choose an answer in 4 methods. So the total no. of possible methods to choose an answer is 4^n. But 4^n=256. Hence n=4. Hence there are 4 Questions in the test. This can be solved using the the nPr
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