Final answer:
Susan's typing rate is 70 words per minute, calculated by dividing 245 words by 3.5 minutes.
Step-by-step explanation:
To find Susan's typing rate, we divide the total number of words typed by the number of minutes spent typing. Susan typed 245 words in 3.5 minutes. The typing rate is calculated as follows:
Typing Rate = Total Words Typed ÷ Total Minutes
Typing Rate = 245 words ÷ 3.5 minutes
Typing Rate = 70 words per minute.
So, Susan's typing rate is 70 words per minute, which corresponds to option b.