Solution:
Given that;
IF THE DAY IS SUNNY, 1000 PEOPLE WILL ATTEND THE BASEBALL GAME.
IF THE DAY IS CLOUDY, ONLY 500 PEOPLE WILL ATTEND.
IF IT RAINS, ONLY 100 PEOPLE
The probability of sunny day, is

The probability of cloudy day, is

The probability of rainy day, is

The number of people expected to attend will be

Hence, the number of people expected is 660