The largest value is 52
The smallest value is 15

We will make 6 classes:

To determine the class width
1. Subtract 52-15 = 37
2. Divide by 6. 37÷6 = 6.166666667
3. Round to 6

The smallest class begins at the smallest number

1st class goes from 15 to 15+6 = 21
2nd class goes from 22 to 22+6 = 28 
3rd class goes from 29 to 29+6 = 35
4th class goes from 36 to 36+6 = 42
5th class goes from 43 to 43+6 = 49
6th class goes from 50 to 50+6 = 56

Classes       frequencies
15 - 21           2
22 - 28           4
29 - 35          17 
36 - 42          13
43 - 49           2   
50 - 56           2
----------------------
Total            40

------------------------------------
Make the histogram, starting and ending
the bars halfway between the class bounds.
I put the frequencies on top of the bars.
(Your teacher may vary from this, as there
is no standard way to do this. Some people
put a vertical frequency axis.)



To determine if it is bell-shaped, we calculate the
mean as 34.325 and the standard deviation as 7.325

1 standard deviation below the mean is 34.325 - 7.325 = 27
1 standard deviation above the mean is 34.325 + 7.325 = 41.65

There are 21 values between those values, 21/40 = .775 = 77.5%
That is within 10% of 68%, so that fits the first part of the
criteria for being bell-shaped:

2 standard deviation below the mean is 34.325 - 2×7.325 = 19.6
1 standard deviation above the mean is 34.325 + 2×7.325 = 48.9

There are 37 values between those values, 37/40 = .925 = 92.5%
That is within 5% of 95%, so that fits the second part of the
criteria of being bell-shaped.

So it is approximately bell-shaped.

Edwin