Answer:
Number of People in the basketball game =A four digit number having 3 in the tens place.
Total number of digits in all={0,1,2,3,4,5,6,7,8,9}=10
So, Required Number,that is number of people at the basketball game which is a four digit number,also digits can repeat
=(0 can't be at Unit place ,so first digit that is number at thousands place can be selected in 9 ways)(Number at Hundred place can be selected in 10 ways )(3 in tens place)( Number at Unit place can be selected in 10 ways )
=9939(Maximum People)
Total number of four digit numbers , if these condition are given
=9×10×1×10
=900