The number of ushers at a basketball game is directly proportional to the number of spectators. If there are 510 spectators at the game, 17 ushers are needed. How many ushers are needed if there are 1,050 spectators?

Using the given information, we can set up a proportion to solve for the number of ushers needed if there are 1,050 spectators:

510 spectators ------ 17 ushers
1,050 spectators ---- x ushers

Cross multiplying, we get:
510 * x = 17 * 1,050
510x = 17,850

Dividing both sides by 510:
x = 35

Therefore, if there are 1,050 spectators at the game, 35 ushers are needed.