Answer:
b. Invalid, because the sample may not be representative of the population.
Step-by-step explanation:
A sample of around 10% of the population is needed to be representative.
In this question:
We have a population of 500,000, and a sample of 10,000.
10,000/500,000 = 1/50 = 0.02 = 2% of the population, so not representative, and option b is correct.
Answer: use socratic you take a picture of the problem and it does it.
Answer:
large = 18 3/4 = 18.75
small = 13/2 = 6 1/2 = 6.5
Step-by-step explanation:
Let l = the weight of large boxes
s = weight of small boxes
2 large and 3 small weights 57
2l+3s = 57
6 large and 5 small wights 145
6l+5s = 145
Multiply the first equation by 3
3(2l+3s) = 57*3
6l +9s =171
Subtract the second equation
6l +9s =171
-6l -5s = -145
-----------------------
4s =26
Divide each side by 4
4s/4 = 26/4
s = 26/4 = 13/2
Substitute this into the first equation
2l +3s = 57
2l + 3(13/2) =57
Multiply by 2 to get rid of the fractions
2(2l + 3(13/2)) =57*2
4l + 39 = 114
Subtract 39 from each side
4l +39-39 = 114-39
4l =75
Divide by 4
4l/4 = 75/4
l = 75/4 = 18 3/4
