We know that, Two quantities in a ratio must be in the same units.
1 m=100 cm⇒2 m=200 cm
Ratio of 15 cm:2 m=15 cm:200 cm=15 cm200 cm=3:40
Now, 1 min=60 sec⇒3 min=180 sec
Ratio of 10 sec:3 min=10 sec:180 sec=10 sec180 sec=1:18
For proportion both ratios must be equal, but 3:4≠1:18.
Hence, they are not in proportion.