To find the probability that a unit will pass inspection (which means it has no defects), you can use the following formula:
\[ \text{Probability of passing} = \frac{\text{Number of units that passed}}{\text{Total number of units inspected}} \]
From the given data:
- Total units inspected = 500
- Units rejected (defective) = 80
First, calculate the number of units that passed inspection:
\[ \text{Units that passed} = \text{Total units} - \text{Units rejected} = 500 - 80 = 420 \]
Now, calculate the probability:
\[ \text{Probability of passing} = \frac{420}{500} = 0.84 \]
To express this as a percentage, multiply by 100:
\[ 0.84 \times 100 = 84% \]
Therefore, the probability that a unit will pass inspection is 84%.