A researcher records the following number of birdcalls made during an experimental session with robins: 7.2 ± 0.6 (M ± SD).Assuming these data are normally distributed,what is the probability that robins made more than nine birdcalls during this experimental session?
A) .9987
B) .4987
C) .0013
D) The probability is not listed in the unit normal table.

Question

Quizplus · Accepted Answer

To solve this problem, we need to use z-score formula:
z = (x - μ) / σ
where,
x = 9 (number of birdcalls we want to find)
μ = 7.2 (mean of birdcalls)
σ = 0.6 (standard deviation of birdcalls)
z = (9 - 7.2) / 0.6 = 3
Using the unit normal table, we can find the probability for z > 3, which is 0.0013. Therefore, the answer is C.

A Researcher Records the Following Number of Birdcalls Made During