PromQL for percentage rate growth values

[mohan garden]

Hi Team,
I have a metric which measures the amount of compute seconds the application has used so far. Example  - 
consumed_minutes{service="B"} 60
total_minutes{service="B"} 6000

now i need to setup alerts where i get alerted if rate of growth of aforementioned consumed metric is very large - 

Q a) the rate of usage growth in last 60 minutes is more than 20% and total usage has exceeded 30% 
Q b) If rate of usage grows from 30 to 50% in last 30 minutes ,


 i think following query should be fine where i compare the growth of last hour with growth of last 2 hours - 

a.1)

( rate(  consumed_minutes[60m]  ) > rate(  consumed_minutes[120m] ) * 1.20  ) and
 ((consumed_minutes  /  total_minutes) * 100)     >   30



a.2) 

( rate(  consumed_minutes[60m]  ) > rate(  consumed_minutes[60m] offset 60m ) * 1.20  ) and
(  (consumed_minutes  /  total_minutes) * 100)     >   30

b.1) 

( rate(  consumed_minutes[60m]  ) > rate(  consumed_minutes[120m] ) * 1.30  ) and  ( rate(  consumed_minutes[60m]  ) < rate(  consumed_minutes[120m] ) * 1.50  ) 

b.2)
( rate(  consumed_minutes[30m]  ) > rate(  consumed_minutes[30m]  offset 30m) * 1.30  ) and  
( rate(  consumed_minutes[30m]  ) < rate(  consumed_minutes[30m] offset 30m) * 1.50  ) 


I am not sure which one out of aforementioned a.1 vs a.2 and b.1 vs b.2 is more accurate. the aforementioned queries are good  or there is more accurate version of the aforementioned queries?
Please advice.