9) B

Total number of incidences of breast cancer = 361 + 65 = 426 cases

We can use approximate values for the estimated person-years lived.
So total number of person-years lived = 153400 + 20000 = 173,400 years
Number of 1000 years = 173,300 / 1000 = 173.4 ~ 170

426 / 170 ~ 425 / 170 ~ 2.5

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s