If every fourth customer gets stickers and every tenth customer gets a notebook, which customer will get both?

1 answer:

6 0

The 20th costumer will get both.
You have to fine the least common multiple of both numbers. So the closest those two numbers have is 20.
$4 \times 5 = 20 \\ 10 \times 2 = 20$

You might be interested in

How do you work this out

Digiron [165]

Check the picture below.

notice, is just a circle inscribed in a square.

now for the first one, we know the diameter is 14, so the square is a 14x14, and the radius of that is half the diameter or 7.

now, if we get the area of the square, which includes the area of the circle, and THEN get the area of the circle and subtract it from the square's, what's leftover is the shaded section.

$\bf \textit{area of a circle}\\\\ A=\pi r^2\\\\
-------------------------------\\\\
\stackrel{\textit{square's area}}{14\cdot 14}~-~\stackrel{\textit{circle's area}}{\pi 7^2}\implies 196-49\pi$

now, for the one on the right-hand-side, the radius is 8, and square's area is 16x16,

$\bf \stackrel{\textit{square's area}}{16\cdot 16}~-~\stackrel{\textit{circle's area}}{\pi 8^2}\implies 256-64\pi$