drawer contains 50 bolts and 150 nuts. Half of the bolts and half of the nuts are rusted. If one item is chosen at random, what is the probability that it is rusted or a bolt ? In a study to test whether there is a difference between the average height of adult females born in two different

Question

drawer contains 50 bolts and 150 nuts. Half of the bolts and half of the nuts are rusted. If one item is chosen at random, what is the probability that it is rusted or a bolt ? In a study to test whether there is a difference between the average height of adult females born in two different 
countries, random samples yielded the following results : 
       n1 = 12O, X1 = 62.7 , S1 = 2.50 
       n2: 150, X2 : 61.8 , S2 = 2.62 
where the measurements are in inches. Use 0.05 level of significance to test the difference between ti-re average heights.

PsyDAG · Answer

First question: one-half = 50%

"X" is typically used to stand for a raw score. If you don't have the symbol, you can write out "mean."

Z = (μ1 - μ2)/Standard error of difference between means (SEμ-μ)

SEμ-μ = √(SEμ1^2 + SEμ2^2)

SEμ = SD/√(n-1)

You are looking for z > 1.96 to reject Ho at .05 level.

I'll let you do the calculations.