What are the distances between the labeled points on the ruler in questions 7-11?

Position of F $= 23.0$
Position of H $= 24.5$

Distance $= \text{Position of H} - \text{Position of F}$
Distance $= 24.5 - 23.0$
Distance $= 1.5$
The distance from F to H is $\boxed{\text{1.5}}$.

8) What is the distance between A and C?

Position of A $= 20.0$
Position of C $= 21.0$

Distance $= \text{Position of C} - \text{Position of A}$
Distance $= 21.0 - 20.0$
Distance $= 1.0$
The distance between A and C is $\boxed{\text{1.0}}$.

9) How far is it from A to K?

Position of A $= 20.0$
Position of K $= 27.0$

Distance $= \text{Position of K} - \text{Position of A}$
Distance $= 27.0 - 20.0$
Distance $= 7.0$
The distance from A to K is $\boxed{\text{7.0}}$.

10) How far is it from B to J?

Position of B $= 20.5$
Position of J $= 26.0$

Distance $= \text{Position of J} - \text{Position of B}$
Distance $= 26.0 - 20.5$
Distance $= 5.5$
The distance from B to J is $\boxed{\text{5.5}}$.

11) What is the distance from C to F?

Position of C $= 21.0$
Position of F $= 23.0$

Distance $= \text{Position of F} - \text{Position of C}$
Distance $= 23.0 - 21.0$
Distance $= 2.0$
The distance from C to F is $\boxed{\text{2.0}}$.

12) The film lasted 153 min, which is ____ min to the nearest 100 min.

Number $= 153$

Since 153 is closer to 200 than to 100 (it is exactly at the midpoint or higher, so it rounds up), it rounds to 200.
The film lasted 153 min, which is $\boxed{\text{200}}$ min to the nearest 100 min.

13) Oxton to Cowster is 197 miles, which is ____ miles to the nearest 10 miles.

Number $= 197$

Since 197 is closer to 200 than to 190, it rounds to 200.
Oxton to Cowster is 197 miles, which is $\boxed{\text{200}}$ miles to the nearest 10 miles.

14) The return trip (from Oxton to Cowster and back) is ____ miles to the nearest 10 miles.

One-way distance $= 197$ miles
Return trip distance $= 197 \times 2 = 394$ miles

Since 394 is closer to 390 than to 400, it rounds to 390.
The return trip (from Oxton to Cowster and back) is $\boxed{\text{390}}$ miles to the nearest 10 miles.

17) Shade in the quadrilaterals.
A quadrilateral is a polygon with four sides.

• Shape A has 5 sides (pentagon).
• Shape B has 4 sides.
• Shape C has 4 sides (rhombus).
• Shape D has 5 sides.
• Shape E has 4 sides. The quadrilaterals are shapes $\boxed{\text{B, C, and E}}$.

18) What is the product of 6 and 21?

Product $= 6 \times 21$

Product $= 126$
The product of 6 and 21 is $\boxed{\text{126}}$.

19) You start with 16 eggs. Half are broken so you throw them away. Half of the broken eggs are too old so you throw them away. You are now left with ____ good eggs.

Broken eggs $= \frac{1}{2} \times 16 = 8$ eggs. These are thrown away.

Good eggs $= 16 - 8 = 8$ eggs.
The information about "half of the broken eggs are too old" refers to the eggs already thrown away and does not affect the count of good eggs.
You are now left with $\boxed{\text{8}}$ good eggs.

20) Twice nine is

Result $= 2 \times 9$

Result $= 18$
Twice nine is $\boxed{\text{18}}$.

21) How many children are in the class?

Total children $= (\text{only black shoes}) + (\text{both}) + (\text{only grey socks}) + (\text{neither})$
Total children $= 11 + 5 + 8 + 3$

Total children $= 27$
There are $\boxed{\text{27}}$ children in the class.

22) How many children are wearing grey socks?

Children wearing grey socks $= (\text{only grey socks}) + (\text{both})$
Children wearing grey socks $= 8 + 5$

Children wearing grey socks $= 13$
There are $\boxed{\text{13}}$ children wearing grey socks.

23) How many are wearing black shoes?

Children wearing black shoes $= (\text{only black shoes}) + (\text{both})$
Children wearing black shoes $= 11 + 5$

Children wearing black shoes $= 16$
There are $\boxed{\text{16}}$ children wearing black shoes.