An oil tank has a capacity of 45 gallons.At the beginning of October it is 80% full.At the end of October it is 1/3 full.How many gallons of oil were used in October?
a. 21
b. 25
c. 41
d. 27
e. 30
my answer is (e)30, 45 x 1/3 =15 ,so 2/3 = 30
45(.80 - 1/3) = 21
The tank was not full at the beginning of the month, but only 80% full, or 36 gallons.
Your answer is correct. At the beginning of October, the tank is 80% full, which is equal to 45 x 0.8 = 36 gallons. At the end of October, the tank is 1/3 full, which is equal to 45 x (1/3) = 15 gallons. Therefore, the amount of oil used in October is 36 - 15 = 21 gallons.
To calculate the gallons of oil used in October, we need to find the difference between the initial amount and the amount at the end of the month.
Step 1: Calculate the initial amount of oil in the tank.
The tank has a capacity of 45 gallons, and it is 80% full at the beginning of October. So, we can find the initial amount by multiplying the capacity (45 gallons) by the percentage (80% = 0.8).
Initial amount = 45 gallons x 0.8 = 36 gallons
Step 2: Calculate the amount of oil at the end of October.
The tank is now 1/3 full at the end of October. To find the amount of oil, we need to multiply the capacity (45 gallons) by the fraction (1/3).
Amount at the end of October = 45 gallons x (1/3) = 15 gallons
Step 3: Subtract the amount at the end of October from the initial amount.
Oil used in October = Initial amount - Amount at the end of October
Oil used in October = 36 gallons - 15 gallons = 21 gallons
So, according to the calculation, the correct answer is (a) 21 gallons, not (e) 30 gallons.