To find the probability that a unit will pass inspection with no defects, we first need to determine the number of units that were not rejected.
From the information provided:
- Total units inspected = 500
- Units rejected due to defect = 80
Now, we can calculate the number of units that passed inspection:
\[ \text{Units that passed} = \text{Total units} - \text{Units rejected} = 500 - 80 = 420 \]
Next, we can calculate the probability that a randomly selected unit will pass inspection (i.e., have no defects):
\[ \text{Probability of passing} = \frac{\text{Units that passed}}{\text{Total units inspected}} = \frac{420}{500} \]
Now, simplify the fraction:
\[ \frac{420}{500} = \frac{42}{50} = \frac{21}{25} = 0.84 \]
Therefore, the probability that a unit will pass inspection with no defects is:
\[ \text{Probability} = 0.84 \]
In percentage terms, this would be 84%.