Let x be the number of winners and y be the number of prize for each winner.
So here total amount for prize money is same i.e.
k=x×y=1,00,000
let x1 prize for 4 people,
⇒4×x1=100000
⇒x1=25000
Similarly,
For 5 people , x2=20000
For 8 people, x3=12500
For 10 people, x4=10000
For 20 people, x5=5000