From the Venn diagram, identify the number of children in the intersection of "grey socks" and "black shoes".

Here are the solutions to the questions:

24) children are wearing grey socks and black shoes.

Step 1: From the Venn diagram, identify the number of children in the intersection of "grey socks" and "black shoes".
The number of children wearing both grey socks and black shoes is 5.
There are $\boxed{\text{5}}$ children wearing grey socks and black shoes.

25) How many children are not wearing black shoes?

Step 1: Identify the groups of children not wearing black shoes. These are children wearing only grey socks and children wearing neither.
Children wearing only grey socks $= 8$
Children wearing neither black shoes nor grey socks $= 3$

Step 2: Sum these numbers.
Total children not wearing black shoes $= 8 + 3 = 11$
There are $\boxed{\text{11}}$ children not wearing black shoes.

26) are not wearing grey socks.

Step 1: Identify the groups of children not wearing grey socks. These are children wearing only black shoes and children wearing neither.
Children wearing only black shoes $= 11$
Children wearing neither black shoes nor grey socks $= 3$

Step 2: Sum these numbers.
Total children not wearing grey socks $= 11 + 3 = 14$
There are $\boxed{\text{14}}$ children not wearing grey socks.

27) I spend 27p. What change should I receive if I give the shopkeeper £1.00?

Step 1: Convert £1.00 to pence.

$$£1.00 = 100\text{p}$$

Step 2: Subtract the amount spent from the amount given.

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