OG详解-OG5 数学1 Q10

Choice B is correct. It’s given that from the sample of 20 employees at the company, 16 of the employees are enrolled in exactly three professional development courses this year. Since (1620​​) is equal to 0.80, or80100​​,  it follows that 80% of the employees in the sample are enrolled in exactly three professional development courses this year. Therefore, the best estimate for the percentage of employees at the company who are enrolled in exactly three professional development courses this year is 80%. It’s given that there are a total of 400 employees at the company. Therefore, the best estimate of the number of employees at the company who are enrolled in exactly three professional development courses this year is(80100​​) (400), or 320.
Choice A is incorrect. This is the number of employees from the sample who aren’t enrolled in exactly three professional development courses this year. Choice C is incorrect. This is the number of employees who weren’t selected for the sample.  Choice D is incorrect and may result from conceptual or calculation errors.