Karen Morrison and Nick Hamshaw Solutions for Exercise 3: Exercise 21.3

Divide:

$60$ in the ratio $3 : 12$

Divide:

$600$ in the ratio $3 : 9$

Divide:

$38$ in the ratio $11 : 8$

Divide:

$300$ in the ratio $11 : 4$

Divide:

$2300$ in the ratio $1:2:7$

In a group of $3200$elderly people, the ratio of men to women is $3:5$. Calculate how many men there are in the group.

Show that the ratio area : circumference for any circle is $r:2$, where $r$is the radius of the circle.

Find the ratio volume : surface area for a sphere of radius $r$, giving your answer as simply as possible.