If your campaign’s daily budget is $20, how much of your budget can be spent to show your ads on certain days, based on fluctuations in traffic?
- Up to 20
- Up to 24
- Up to 21
- Up to 30
When your ads are shown more often, your total daily cost might be up to 20% more than your average daily budget. However, you won’t be charged more than your average daily budget multiplied by the average number of days in a month (30.4).
Read more here: https://support.google.com/adwords/answer/2375423?hl=en