Since each participant has an equal chance of receiving one of the three types of coupons (skiing, snow tubing, or sleigh rides), the probability of each participant receiving a coupon for sleigh rides is \( \frac{1}{3} \).
To find the expected number of participants who receive a coupon for sleigh rides out of 900 people, you can multiply the total number of participants by the probability of receiving a sleigh ride coupon:
\[ \text{Expected number of sleigh ride coupons} = 900 \times \frac{1}{3} = 300 \]
Thus, the expected number of people who would receive a coupon for sleigh rides is 300.