Question

A hotel maintenance crew wants to estimate how many of the 12,000 lamps in their 30-story hotel need a new light bulb. Which of the following is a random sample of lamps to be inspected?(1 point)
Responses

all lamps from the rooms with king-sized beds
all lamps from the rooms with king-sized beds

100 lamps on each floor chosen randomly
100 lamps on each floor chosen randomly

400 lamps on the first 10 floors
400 lamps on the first 10 floors

all lamps in booked rooms
all lamps in booked rooms

Answer 1

100 lamps on each floor chosen randomly.

This gives a random (stratified) selection across all floors so lamps throughout the hotel are represented, whereas the other choices select by a nonrandom criterion or only part of the hotel.