I want to be able to convert a decimal into time, and am completely stuck!

As an example, I have in cell A1 4.9 (this number represents 4.9hrs).

I want a formula that will calculate the hours and minutes for me, and show
the result in normal time format. In my example above the answer I would be
looking for is 04:54 (i.e. four hours and 54 minutes).

I have trawled these threads and have found many posts on how to convert
time to a decimal. I want to do the reverse.

Any ideas?

Darrell.