math qwestion plz help

Question

Gianna runs her first lap around the track in 4.35 minutes, her second lap in 3.9 minutes and her third lap in 5.102 minutes. What was her total time for the three laps? 

5.576 min

8.25 min

13 min

13.352 min

Answer 1

13.352 minutes for all 3 laps

punch the 3 numbers into a calculator: 4.35 + 3.9 + 5.102

one clue is the last number 5.102 ends in a 2.

Only 13.352 also ends in a 2

or add the 4, 3 and 5 to get 12. the sum is at least 12, that narrows the answer down to the last two choices 13 or 13.352

since the 3rd lap involves a number with 3 decimals, the answer should also have 3 decimals.