gbq puzzle

[stormin]

In the good old days of Window tax an owner of a 30 sq ft window had to pay �105 in tax, while an owner of a 60 sq ft window had to cough up �195.  On this reckoning how much tax would a 90 sq ft window have incurred?

[THECORBYLOON]

I thought window tax was based on the number of windows rather than the size but anyway, here's my answer.

As the doubling of the window area does not result in a doubling of the tax, I have assumed the tax is based on a constant plus an amount per square foot. This works out to be �15 for each window and �3 per sq foot.

�15 + (30 x �3) = 105 and �15 + (60 x �3) = 195

So, for a window of 90 sq ft the tax is-

�15 + (90 x �3) = �285

[stormin]

Thanks corbyloon your thinking is very much the same as mine but the question setter is as tricky as a bagful of monkeys.  Unless there is a better answer of course.....

[landie]

Plot the two values on a graph. Thecorbyloon has given you the correct answer when the two points are intersected by a staight line.

You can get other answers if you intersect with curves.

[heatherglen]

I got the answer of �285 by adding on the difference between �90 and �195!