This is grouped data so unless you have the raw data, you're going to have to do something to recreate variation in your data. For simplicity we can assume a flat distribution - dogs are as equally likely to be 0 as 5.
REPT() function to output a comma-separated list of numbers representing each group.
=REPT(B2&",",C2) --- where B2 is your group upper bound and C2 is the group frequency
At the bottom, concatenate each of those strings into one large string:
Copy this string and Paste Special as Values in a new worksheet. Use the Text to Columns tool on the Data ribbon tab to split the data into one column per value. Copy this entire range, then Paste Special and Transpose to flip this into a vertical list of values. Your data should look something like this:
Feel free to discard the horizontal row - we don't need it. Now we want to interpolate some values in column B, using a formula something like:
Breaking this down, we have:
=(5* -- your groups are increments of 5
COUNTIF($A$4:A5,A5) -- how far down a row is within a group
COUNTIF($A$4:$A$5000,A5) -- what the frequency is for that group
+(A5-5) -- add this result to the lower bound
Now, you can use the
QUARTILE() function on this list of estimated values to approximate your quartiles: