Question

The time that people require to react to a stimulus usually has a right-skewed distribution, as lack of attention or tiredness causes some lengthy reaction times. Reaction times for children with attention deficit hyperactivity disorder (ADHD) are more skewed, as their condition causes more frequent lack of attention. In one study, children with ADHD were asked to press the spacebar on a computer keyboard when any letter other than X appeared on the screen. With 2 seconds between letters, the mean reaction time was 449 milliseconds (ms) and the standard deviation was 81 ms. Take these values to be the population μ and σ for ADHD children. (Round your standard deviations to two decimal places.)

What are the mean and standard deviation of the mean reaction time x for a randomly chosen group of 15 ADHD children?

mean	ms
standard deviation	ms

What are the mean and standard deviation of the mean reaction time x for a randomly chosen group of 150 ADHD children?

mean	ms
standard deviation	ms

Answer 1

Solution :

mean = = 449

standard deviation = = 81

1) n = 15

Mean = =    = 449

Standard deviation = = / n =81 / 15 = 20.9141

2)n = 150

Mean = =    = 449

Standard deviation = = / n =81 / 150 = 6.6136