First blank: not random Because he sent it to the top 5 students. Not random students throughout the grade.
second blank: I would guess not valid because it was not a random sample.
2.5 ounces = 0.15625 pounds
Scale: 1 unit : 5 feet
Regular Dimensions: 120 ft by 75 ft
Scale Dimensions: 24 units by 15 units
I hope this helps. (:
A random sample is one in which there is an equal chance of picking any item from a population.
So it is unbiased.
True