Posted by Meep on .
A Kansas University research station wishes to investigate if a new variety of wheat is more resistant to a disease than an old variety. It is known that this disease strikes approximately 15% of all plants of the old variety. A field experiment was conducted, and of 120 new plants, 12 became infected.
The calculated value of the test statistic is:
1.83
1.10
1.53
1.53
1.83

AP Statistics 
MathGuru,
You can try a proportional onesample ztest for this one since this problem is using proportions.
Using a formula for a proportional onesample ztest with your data included, we have:
z = .1  .15 >test value (12/120) is .1) minus population value (.15) divided by
√[(.15)(.85)/120] > .85 represents 1.15 and 120 is sample size.
Finish the calculation.