The answer choices are in cubic inches, so convert the dimension that is given as feet into inches.
1 foot = 12 inches, so multiply 3.1 feet by 12:
3.1 x 12 = 37.2 inches.
Now multiply the three dimensions to find the volume:
15 x 37.2 x 7 = 3,906 in^3
8 meters increased by 25 : (8 + 25) = <em>33 meters</em>
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If you really meant to say "increased by <u><em>25 percent</em></u>" . . .
25 percent means 0.25
0.25 x 8 = 2 <== that's the increase
8 + 2 = <em>10 meters</em>
