Need help with this uw biostats q

[Northerncardinal]

How do we calculate the total population size (denominator for calculating mean) from the histogram in this question???

Question's pic is attached.

Thanks!

---

Members don't see this ad.

 

[Ven0m]

I could be wrong but isn't the total just 100? Add up the number of patients for each x value tested (50+30+10+10 = 100 patients tested each day, this histogram is for the 13th day). 50 people got 0, 30 people got 1, 10 people got 2, 10 people got 3. so (50*0)+(30*1)+(10*2)+(10*1) = 80 total anginas, over a total of 100 people = 80/100 = 0.8 anginas per day on average; my answer is A. I haven't really started studying for USMLE biostats so I'm probably wrong.

 

[dempty]

I could be wrong but isn't the total just 100? Add up the number of patients for each x value tested (50+30+10+10 = 100 patients tested each day, this histogram is for the 13th day). 50 people got 0, 30 people got 1, 10 people got 2, 10 people got 3. so (50*0)+(30*1)+(10*2)+(10*1) = 80 total anginas, over a total of 100 people = 80/100 = 0.8 anginas per day on average; my answer is A. I haven't really started studying for USMLE biostats so I'm probably wrong.

You got it. It's 0.8. Just multiply the weight by the corresponding value and sum the products.