Define the word medium

On november 25th, beginning checking balance is $100 account credited for a deposit of $50. account has $150that same day, two checks are posted totaling $75.$150-$75 = $75will an overdraft occur if sherri's bank credits deposits before it posts checks? nowill an overdraft occur if sherri's bank posts checks before it credits deposits? no

Answerfrom the mid 19th century to the 20th and on : )