Convert minutes to HH:MM

Hi All;

belwo is my query to convert minutes to HH:Mm

CONVERT(float, CAST((appt.scheduleddurationminutes/60) AS VARCHAR(8))+ '.' + CAST(( appt.scheduleddurationminutes%60)AS VARCHAR(2))) as Duration,

which gives me outputs as below

But when used in SSRS to add all the Duration field it get displayed as 11:7 but it should get displayed as 12:10

Any help on this much appreciated

Thanks

Pradnya07