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