Disabled student needs assistance

I have math dyslexia and have repeated every math class at least once in order to pass.

I am now in Stats and all these numbers and formulas stress me out

we were given the following numbers:
1.00 1.76 18.04 26.34 39.24


We are to find mode, mean, median, stddev and variance (by hand)

Mode = 86.38
mean = (1.00 + 1.76+ 18.04 + 26.34 + 39.24 / n)= 17.26
median = 18.04
stddev =
variance = stddev^2

according to excel and an online calc, the stddev is 16.36136 -but I have not clue as to how they got that number?

Thanks for any assistance.
Miss Dianna

MissDianna said:

I have math dyslexia and have repeated every math class at least once in order to pass.

I am now in Stats and all these numbers and formulas stress me out

we were given the following numbers:
1.00 1.76 18.04 26.34 39.24


We are to find mode, mean, median, stddev and variance (by hand)

Mode = 86.38
mean = (1.00 + 1.76+ 18.04 + 26.34 + 39.24 / n)= 17.26
median = 18.04
stddev =
variance = stddev^2

according to excel and an online calc, the stddev is 16.36136 -but I have not clue as to how they got that number?

Thanks for any assistance.
Miss Dianna

Click to expand...

Equation for calculating stdev is:

\(\displaystyle (stdev)^2 \ = \ \frac{\sum_{i=1}^n (x_i \ - \ mean)^2}{n-1}\)

so x1 is the total of all the numbers - 18.04 / 5-1 ?

The best thing to do is run it through Excel or a calculator to find the standard deviation.

But, if you have to do it by hand the S.D can be found from the formula:

\(\displaystyle \sqrt{\frac{\sum(x-\overline{x})^{2}}{n-1}}\)

If this looks befuddling, let me spell it out.

The x is the value of each speicific point, the \(\displaystyle \overline{x}\) is the mean or average.

\(\displaystyle \sum(x-\overline{x})^{2}\) means we subtract the mean from each data point, square it, then add them all up.

n is how many points there are. In this case, 5. So, n-1=4.

Step through it:

The mean is \(\displaystyle \overline{x}=\frac{1+1.76+18.04+26.34+39.24}{5}=17.276\)

\(\displaystyle \sum(x-\overline{x})^{2}=(1-17.276)^{2}+(1.76-17.276)^{2}+(18.04-17.276)^{2}+(26.34-17.276)^{2}+(39.24-17.276)^{2}=1070.81152\)

Divide that by n-1=4, then take the square root.

\(\displaystyle \sqrt{\frac{1070.81152}{4}}=16.361\)