If 5cm on a map represents 2.5km of actual ground, how many centimetres would 15km of actual ground be on the map?

30cm

Step-by-step explanation:

5cm = 2.5km

xcm = 15km

Do cross multiple

2.5x = 5×15

x = (5×15) ÷ 2.5

=30cm

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

source:  

0.4 liters = 400 milliliters (multiply the volume value by 1000 and it give you the answer). hope this ! ^-^