WEST DES MOINES, Iowa – The 29 lotteries, including the Maine State Lottery, that participate in the Powerball game have voted to make changes that will boost the average jackpot size but decrease the chance of winning.

Starting Aug. 29, the beginning jackpot will increase to $15 million from the current $10 million, the Multi-State Lottery Association announced Wednesday. The top prize will grow by no less than $5 million between each drawing.

“Lottery games need to be changed from time to time, to respond to both player demands and population changes,” said Randy Davis, president of the Louisiana Lottery Corp. and chairman of the Powerball Game Group.

To boost the jackpot size, two numbers will be added to the first pool in the game, meaning players will choose five numbers from one to 55. The current first draw picks five white balls from a pool of 53.

The Powerball is drawn from a separate pool of red balls numbered from one to 42. That will not change.

The larger number of white balls decreases the chances of winning the jackpot to 1 in 146.1 million. The current game has jackpot odds of 1 in 120.5 million.

Ed Stanek, Iowa Lottery chief executive and one of Powerball’s co-inventors, said the changes are part of a popular product’s evolution.

The chance of winning a cash prize in the game will be cut slightly, to 1 in 36.60 from 1 in 36.06, lottery officials said.