Question

a student attendsa50 Marks test. no negative marks are given in the test.find the probability that he scores 30 or 35.explain in detail

Answer 1

full marks =50
if 30 marks =30/50=3/5
if 35 marks =35/50=7/10

if there are 2 answers to this question then it is 
probability for coming 30=3/5
probability for coming 35=7/10
 but if it is a single answer then i may take a guess .
 

Answer 2

Since no negative marks are given in the test,
Possible outcomes=(0,1,2,3,4.........50) 
Number of possible outcomes=51
Probability of scoring 30=1/51 (since there is only 1 chance of 30 coming)
Probability of scoring 35=1/51 (same reason as above)
Total probability=1/51+1/51=2/51.
Ans:The probability that he scores 30 marks or 35 marks is 2/51.