Question

CHALLANGE




FOR EVERY MATH GENIUS




x2 - 3|x - 2| - 4x = - 6(find X)


An examination consists of three parts. In part A, a student must answer 2 of 3 questions. In part B, a student must answer 6 of 8 questions and in part C, a student must answer all questions. How many choices of questions does the student have?


​

Answer 1

Answer:

Total no. of questions in part A =6

Total no. of questions in part B =7

A student can choose 10 questions from the given 13 questions in the following pattern-

4 from part A and 6 from part B

5 from part A and 5 from part B

6 from part A and 4 from part B

∴ Total no. of ways can the student choose 10 questions =(

6

C

4

×

7

C

6

)+(

6

C

5

×

5

C

5

)+(

6

C

6

×

7

C

4

)

As we know that,

n

C

r

=

r!(n−r)!

n!

∴ total no. of ways can the student choose 10 questions =(15×7)+(6×21)+(1×35)=266

Hence the no. of ways can the student choose 10 questions are 266.

Hence the correct answer is 266.