AP Statistics Practice Test 1
SECTION II
Time: 1 hour and 30 minutes
Number of questions: 6
Percentage of total grade: 50
General Instructions
There are two parts to this section of the examination. Part A consists of five equally weighted problems
that represent 75% of the total weight of this section. Spend about 65 minutes on this part of the exam.
Part B consists of one longer problem that represents 25% of the total weight of this section. Spend about
25 minutes on this part of the exam. You are not necessarily expected to complete all parts of every
question. Statistical tables and formulas are provided.
• Be sure to write clearly and legibly. If you make an error, you may save time by crossing it out rather
than trying to erase it. Erased or crossed-out work will not be graded.
• Show all your work. Indicate clearly the methods you use because you will be graded on the
correctness of your methods as well as the accuracy of your final answers. Correct answers without
support work may not receive credit.
Statistics, Section II, Part A, Questions 1–5
Spend about 65 minutes on this part of the exam; percentage of Section II grade: 75.
Directions: Show all your work. Indicate clearly the methods you use because you will be graded on
the correctness of your methods as well as on the accuracy of your results and explanation.
In response to drought, some plants react with reduced biological nitrogen fixation (BNF), hindering
their ability to grow at a typical rate. Scientists are working to develop techniques to supplement
crops so that the BNF rate is not as greatly reduced during drought. One promising treatment is to be
compared to standard growing conditions on randomly selected acres of soybeans. The following
summary data is for the bushels per acre of soybeans for each group:
a. The maximum yield of the treated acres was 51.50 bushels of soybeans. Is this an unusually high
yield compared to the other treated acres? Justify your answer.
b. Researchers indicate that the average yield for the treatment group is statistically significantly
higher than that of the control group. Explain what this means in simple terms.
c. Field workers report to the scientists that the machine to measure the yield in the treatment group
was poorly calibrated—each of the bushel values was over-reported by 0.5 bushels. So each of