Chapter 10 Counting Methods and Probability - 10.3 Define and Use Probability - 10.3 Exercises - Problem Solving - Page 704: 42a

See below

Find the number of ways we can choose 2 cards out of 5: $_5 C_2=\frac{5!}{(5-2)!.2!}=10$ There is only one way for two chosen cards to be a 3 or 4. The probability that the two numbers chosen are 3 and 4: $P(A)=\frac{1}{10}=0.1$