In the mining process each miner will create a block with the transactions found in the pool and will start the calculation of nonce, the miner with greater hash power will finish the job first and announce the block.
When the process starts the miners will start the calculation again(the slowest and the fastest), imagine that we have 2 pools of mining and the slower needs 2 hour to calculate a nonce and the faster 2 minutes, the window of 10 minutes will have a winner and the slower have to start the caculation again.
How does lottery work to the solve this problem?