A researcher records the following response times to a visual stimulus: 23 ± 3.1 (M ± SD)s.Assuming these data are normally distributed,what is the probability that participants responded in 20 s or less?
A) .1660
B) .3340
C) .6660
D) The probability is not listed in the unit normal table.

Question

Quizplus · Accepted Answer

To find the probability of participants responding in 20 seconds or less, we need to standardize the value using the formula z = (x - μ) / σ. Here, x = 20, μ = 23, and σ = 3.1. Plugging in the values, we get z = (20 - 23) / 3.1 = -0.968. Looking up this value in the unit normal table gives us a probability of 0.1660, which is option A.

A Researcher Records the Following Response Times to a Visual