The formula for variance is:

The formula for variance is:

$$s^2 = \frac{\sum fx^2}{N} - \left(\frac{\sum fx}{N}\right)^2$$

Substitute the given values:

$$s^2 = \frac{10468.9}{80} - \left(\frac{909}{80}\right)^2$$

Perform the division:

$$s^2 = 130.86125 - (11.3625)^2$$

Calculate the square:

$$s^2 = 130.86125 - 129.00640625$$

Subtract the values:

$$s^2 = 1.85484375 \text{ (g/100ml)}^2$$

Rounding to two decimal places:
The variance is $\boxed{1.85 \text{ (g/100ml)}^2}$.

The range is estimated as the difference between the upper class boundary of the highest class and the lower class boundary of the lowest class.

Upper class boundary of 14.0-14.9: $14.9 + 0.05 = 14.95$
Lower class boundary of 8.0-8.9: $8.0 - 0.05 = 7.95$

Calculate the range:

$$\text{Range} = 14.95 - 7.95 = 7.0 \text{ g/100ml}$$

The range is $\boxed{7.0 \text{ g/100ml}}$.

b) Step 1: Identify the classes with haemoglobin levels less than 11.0 g/100ml.
The classes with haemoglobin levels less than 11.0 g/100ml are:

• 8.0-8.9
• 9.0-9.9
• 10.0-10.9