28,000 x 25% = 7,000
28,000 + 7,000 = 35,000
If the smaller number is x, then the larger number has to be 20 - x in order for the arithmetic mean to be 10, as their sum must be 20.
If the geometric mean is 8 the product of the numbers has to be 64 and so the larger number is 64/x
Solving 64/x = 20 - x gives the quadratic x^2 -20x +64 = 0 so x = 4 or 16.
The two numbers are 4 and 16.
<span>The
graph of y against x in inverse proportion is a rectangular hyperbola
but I don't see at all how this knowledge/observation is any help in
solving the problem.
Inverse proportion means that as x doubles y will halve and the equation
is xy = k where k is some number. A good example of inverse proportion
is speed and time taken over some fixed distance. In this case x could
represent the speed (mph) and y the time (h) and then k is the distance
in miles.
Since we know y=3 when x=2 we have xy = 6. Now it's easy to see when x=6 y=1.</span>
Graph 3 is the answer. Choose a point on the line. Go down by 3. Then go to the right by 5.
