If the number of ushers is directly proportional to the number of spectators, we can use the proportionality relationship to find the number of ushers needed for 1050 spectators.
Given:
- 510 spectators require 17 ushers.
We can set up the proportion:
\[ \frac{17 \text{ ushers}}{510 \text{ spectators}} = \frac{x \text{ ushers}}{1050 \text{ spectators}} \]
Cross-multiplying gives us:
\[ 17 \times 1050 = 510 \times x \]
Calculating \(17 \times 1050\):
\[ 17 \times 1050 = 17850 \]
Now we have:
\[ 17850 = 510 \times x \]
To find \(x\), divide both sides by 510:
\[ x = \frac{17850}{510} \]
Calculating that:
\[ x = 35 \]
Thus, the number of ushers needed for 1050 spectators is 35 ushers.