Question: The number of distinct rational numbers x such that $ 0<x<1 $ and $ x=\frac{p}{q}, $ where $ p,q\in {1,2,3,4,5,6}, $ is
Options:
A) 15
B) 13
C) 12
D) 11
Show Answer
Answer:
Correct Answer: D
Solution:
- [d] As $ 0<x<1, $ we have $ p<q $ The number of rational numbers $ =5+4+3+2+1=15. $ When p, q have a common factor, we get some rational numbers which are not different from those already counted. There are 4 such numbers: $ \frac{2}{4},\frac{2}{6},\frac{3}{6},\frac{4}{6} $ Therefore, required number of rational numbers $ =15-4=11. $