Chapter 12 - Counting and Probability - Section 12.3 Probability - 12.3 Assess Your Understanding - Page 886: 61

$0.5$

We know that probability$=\frac{\text{number of favorable outcomes}}{\text{number of all outcomes}}.$ We have $3+5=8$ chips and numbers in total (total outcomes). There are $3+1=4$ chips that are striked or are $1$ (favorable outcome). Thus, the probability is: $P=\frac{4}{8}=0.5$