A headline in a certain newspaper states that \"most stay at first job less than

Question

A headline in a certain newspaper states that "most stay at first job less than 2 years." That headline is based on an online poll of 390 college graduates. Among those polled, 50% stayed at their first full-time job less than 2 years. Is the actual number of surveyed graduates (273 graduates) who stayed at their first job less than two years unusual? 1) Since the actual number is outside the range of usual values, it is unusual 2) Since the actual number is inside the range of usual values, it is unusual. 3) Since the actual number is inside the range of usual values, it is not unusual.

Explanation / Answer

here mean =np=390*0.5=195

std deviaiton =sqrt(np(1-p))=9.874

as usual values are within 2 std deviation from mean

hence usual range =mean -/+ 2*std deviation=195 -/+2*9.874 =175.25 to 214.75

as 273 falls outside of this range ; correct answer is:

option1: since the actual number is outside the range of usual values ; it is unusual.

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