How the air temperature changed: a) first increased by 25%, and then decreased

How the air temperature changed: a) first increased by 25%, and then decreased by 40%; b) first decreased by 60%, and then increased by 80%.

a) We take the initial temperature value equal to 100%.

Thus, after increasing by 25%, it was:

100% + 25% = 125% (of starting temperature).

After the new temperature decreased by 40%, it was:

125% * (100% – 40%) / 100% = 125% * 60% / 100% = 75%.

This means the temperature has dropped by:

100% – 75% = 25%.

Answer:

Decreased by 25%.

b) By analogy with the first task.

100% – 60% = 40%.

40% * (100% + 80%) / 100% = 40% * 180% / 100% = 72%.

100% – 72% = 28%.

Answer:

Decreased by 28%.



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