There are 3 5-passenger taxis available so that's 3 x 5 = 15 total seats. There are 20 people needing transportation leaving 20 - 15 = 5 who will have to find other transportation.

To simplify a radical, factor out the perfect squares:

\( \sqrt{50} \)
\( \sqrt{25 \times 2} \)
\( \sqrt{5^2 \times 2} \)
5\( \sqrt{2} \)

To subtract these radicals together their radicands must be the same:

9\( \sqrt{20} \) - 5\( \sqrt{5} \)
9\( \sqrt{4 \times 5} \) - 5\( \sqrt{5} \)
9\( \sqrt{2^2 \times 5} \) - 5\( \sqrt{5} \)
(9)(2)\( \sqrt{5} \) - 5\( \sqrt{5} \)
18\( \sqrt{5} \) - 5\( \sqrt{5} \)

Now that the radicands are identical, you can subtract them:

You have 2 out of the total of 100 raffle tickets sold so you have a (\( \frac{2}{100} \)) x 100 = \( \frac{2 \times 100}{100} \) = \( \frac{200}{100} \) = 2% chance to win the raffle.

The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:

\( \frac{7}{100} \) x 9 = \( \frac{7 \times 9}{100} \) = \( \frac{63}{100} \) = 0.63 errors per hour

So, in an average hour, the machine will produce 9 - 0.63 = 8.37 error free parts.

The machine ran for 24 - 4 = 20 hours yesterday so you would expect that 20 x 8.37 = 167.4 error free parts were produced yesterday.