# Math Help - median, semi-interquartle range, of grouped data

1. ## median, semi-interquartle range, of grouped data

my question is on part b, my ans is different form the working. ans given is median=17 years 1 month, semi-interquartle range is 10 months . which part is wrong?

2. ## Re: median, semi-interquartle range, of grouped data

firstly the formula for median should be $L+C(\frac{\frac{N}{2}-F}{f})$ where $f$ is the frequency, of the class the median is in, not the cumulative frequency like how you used it. same goes for the formula for first and third quartile.
however i tried using the correct formula but still did not get the correct answer. i must be missing something