Respuesta :
Step-by-step explanation:
the numbers of the problems =
12 × 25 = 300
each minute he can answer 2 problems
therefore, the time that he expect to finish the problems =
300/2 × 1 minute = 150 minutes
= 2 hours and 30 minutes
2 questions he can solve 1 min
per question he need 1/2min or 0.5min
Now
Total problems
- 25(12)
- 300
Total time
- 300(0.5)
- 150min
- 2h 30min