The price of a barrel of oil was $40.45 last month. The price has increased by 15%.
How much is a barrel of oil today, rounded to 10^{-2} ?
Assume the initial price is x and the change in price is y%. Then the new price is:
x \cdot \left(1 + \dfrac{y}{100}\right)
The price of a barrel of oil today is:
$40.45 \times\left(1+.15\right)=$46.52
The price of an barrel of oil today is $46.52.
A car is traveling 60mph and it slows down 20%.
What is the current speed?
Assume the initial speed is x and the change in speed is y%. Then the new speed is:
x \cdot \left(1 + \dfrac{y}{100}\right)
The car is moving at:
60 \times\left(1-.2\right)=48 mph
The car is now moving at 48mph.
Tesla model S can travel 300 miles on a full charge. Due to new efficiencies they found a way to add 12% more range to the model S.
What is the new range of the Tesla model S?
Assume the initial range is x and the change in range is y%. Then the new range is:
x \cdot \left(1 + \dfrac{y}{100}\right)
The new range is:
300 \times\left(1+.12\right)=336 \text{ miles }
The new range is 336 miles.
A plane cruises at 10,000 ft and drops its elevation by 20%.
What is the new elevation of the plane?
Assume the initial elevation is x and the change in elevation is y%. Then the new elevation is:
x \cdot \left(1 + \dfrac{y}{100}\right)
The elevation is:
10\ 000 \times \left(1-.20\right)=8{,}000 \text{ ft.}
The new elevation is 8,000 ft.
A train is moving 80mph.
The speed increases by 25%, what is the new speed?
Assume the initial speed is x and the change in speed is y%. Then the new speed is:
x \cdot \left(1 + \dfrac{y}{100}\right)
The speed of the train is:
80 \times \left(1 + .25\right) = 100 mph
The speed of the train is 100mph.
The population of the world was 6 billion in 2000. The population has increased by 27%. What is the current world population?
Assume the initial population is x and the change in price is y%. Then the current population is:
x \cdot \left(1 + \dfrac{y}{100}\right)
Therefore, the world population is:
6 \times\left(1+0.27\right)=6 \times 1.27 = 7.62 \, \text{billion}
The total world population is 7.62 \, \text{billion} today.
The price of caviar was $70.15 last month. The price has increased by 20% .
How much is caviar today, rounded to 10^{-2} ?
Assume the initial price is x and the change in price is y%. Then the new price is:
x \cdot \left(1 + \dfrac{y}{100}\right)
The price of caviar today is:
$70.15 \times\left(1+.20\right)=$84.18
The price of caviar today is $84.18.