# Standard deviation query

#### johnuk

##### New member
I am completely lost with standard dev and have to do it as part of a lean course for work. The question I have been set is probably very simple, but I want to know the workings to get to the answer:

a population has a mean of 51 and a standard deviation of 3.4. If repeated samples of 20 units are taken from this population, what is the likely standard dev of the sample means

0.76
3.4
0.17
2.55

#### tkhunny

##### Moderator
Staff member
I am completely lost with standard dev and have to do it as part of a lean course for work. The question I have been set is probably very simple, but I want to know the workings to get to the answer:

a population has a mean of 51 and a standard deviation of 3.4. If repeated samples of 20 units are taken from this population, what is the likely standard dev of the sample means

0.76
3.4
0.17
2.55
Sample size 20... Is there a square root in your denominator future?

#### Dr.Peterson

##### Elite Member
I am completely lost with standard dev and have to do it as part of a lean course for work. The question I have been set is probably very simple, but I want to know the workings to get to the answer:

a population has a mean of 51 and a standard deviation of 3.4. If repeated samples of 20 units are taken from this population, what is the likely standard dev of the sample means

0.76
3.4
0.17
2.55
Presumably you will have been given a formula for the standard deviation of the sample means. It involves a square root.