In an examination of n questions, a student replied 15 out of the first 20 questions correctly. Of the remaining questions, he answered onethird correctly. All the questions have the same credit. If the student gest 50% marks, the value of n is? 


(a) 
20 
(b) 
40 
(c) 
50 
(d) 
100 
In an examination of n questions, a student replied 15 out of the first 20 questions correctly. Of the remaining questions, he answered onethird correctly. All the questions have the same credit. If the student gest 50% marks, the value of n is? 


(a) 
20 
(b) 
40 
(c) 
50 
(d) 
100 