2 votes 2 votes Consider $30$ multiple-choice questions, each with four options of which exactly one is correct. Then the number of ways one can get only the alternate questions correctly answered is $3^{15}$ $2^{31}$ $2 \times \begin{pmatrix} 30 \\ 15 \end{pmatrix}$ $2 \times 3^{15}$ Combinatory isi2014-dcg combinatory + – Arjun asked Sep 23, 2019 • recategorized Nov 12, 2019 by Lakshman Bhaiya Arjun 959 views answer comment Share Follow See all 13 Comments See all 13 13 Comments reply Show 10 previous comments Hradesh patel commented Jan 4, 2020 reply Follow Share What are three option of false.??? I think its ( wrong, not attempted) 2 ways Plz explain?? 0 votes 0 votes Verma Ashish commented Jan 4, 2020 reply Follow Share Out of 4 options for each question only one option is correct..rest 3 are false 1 votes 1 votes Hradesh patel commented Jan 4, 2020 reply Follow Share Ok,...i missed.. thanks 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes The answer pattern can be: CWCWCW…...CW, or WCWCWC…...WC For first case: each W has 3 choices and each C has only 1 choice => 3^15 choices for second case: 3^15 case, from similar logic as first case. so, total ways = 2*(3^15) neeraj_bhatt answered Sep 5, 2020 neeraj_bhatt comment Share Follow See all 0 reply Please log in or register to add a comment.