In a certain experiment, the data collected is the number of organisms per sample, and this data ...
In a certain experiment, the data collected is the number of organisms per sample, and this data follows a normal distribution. If the sample of data has a mean of 60 and a standard deviation of 12, which of the following is exactly 1.95 standard deviations more than the mean?
Answer/Solution
e) 83.4
Steps/Work
Standard Deviation is a relatively rare category in the Quant section, although you're like to be tested on it 1 time on Test Day. You'll never be asked to calculate SD though, so you really just need to learn the basic 'concepts' behind it.
Here, we're told two things about a group of numbers:
1) The average of the group is 60
2) The standard deviation of the group is 12
If you go 1 SDupfrom the average, you hit.....60+12 = 72
If you go 1 SDdownfrom the average, you hit.....60-12 = 48
If you go 2 SDsupfrom the average, you hit.....60+2(12) = 84
If you go 2 SDsdownfrom the average, you hit.....60-2(12) = 36
Etc.
Here, we're asked for the number that is EXACTLY 1.95 SDs above the mean....
1.95 SDsupwould be.....60 + 1.95(12) = 83.4
E
Here, we're told two things about a group of numbers:
1) The average of the group is 60
2) The standard deviation of the group is 12
If you go 1 SDupfrom the average, you hit.....60+12 = 72
If you go 1 SDdownfrom the average, you hit.....60-12 = 48
If you go 2 SDsupfrom the average, you hit.....60+2(12) = 84
If you go 2 SDsdownfrom the average, you hit.....60-2(12) = 36
Etc.
Here, we're asked for the number that is EXACTLY 1.95 SDs above the mean....
1.95 SDsupwould be.....60 + 1.95(12) = 83.4
E