How to convert a numeric value into a time format inside a formula that also contains a string

I have a "mixed" formula (containing numbers and text) and I need to convert the numeric values into a time format.

Here is my formula:

=count(J8:J11)*2/24&" / "&sum(K8:K11)

And here is the resulting cell value:

0.333333333333333 / 0.204861111111111

What I want to see is:

8:00 / 4:55

How can I transform these long numbers into a time format as such?