A company of 640 part-time employees is growing and decided to promote 80 of these employees into full-time employees. This promotion rate of ? 1 in 6 1 in 8 1 in 16 1 in 64 1 in 80

The promotion rate can be calculated by dividing the number of employees promoted by the total number of employees and then multiplying by 100 to get the percentage. In this case, the promotion rate is (80/640) * 100 = 12.5%. This means that 1 in 8 employees is promoted. Therefore, the correct answer is 1 in 8.