Algebra - How to find the percent of decrease

When performing a Google search for "Lions" the amount of search results are 257 million. After refining the search to "African Lions" the amount of search results is 6.7 million. What is the percentage change by going from a search for "Lions" to "African Lions"? (Round the answer to one decimal place)

Explanation

The percent change formula new amount subtracted by old amount then divided by old amount and multiplied by 100 should be used for this problem. The new amount is 6.7 million and the old amount is 257 million. It is not necessary to use the expanded numbers 6,700,000 or 257,000,000 to work out the problem but it will also work.

$\frac{6.7-257}{257}\cdot100$

$\frac{-250.3}{257}\cdot100$

$-0.9739\cdot100$

By refining the search, the amount of search results fell by 97.4%

For your 16th birthday, your parents have decided to help you buy a car. The car you want costs $2500. Your parents said they would contribute $700 toward the purchase price of the car. What was the percent decrease in the price you have to pay for the new car after their contribution?

$\textup{None of the other answers}$

Explanation

To calculate the percent decrease in a price, quantity etc. you need to establish a ratio between the new and lower price and the old, higher price. Then convert to a percentage by multiplying by 100.

Establish a ratio between the new and the old:

$\frac{1800}{2500}=.72$

Convert to a percentage:

percent

So the parental discount amounts to 72% of the old price. In other words with their help, you will only pay 72% of the original price. Because you are now paying only 72% of that price, that was a decrease of 28% (100-72=28%).

Alternatively find the difference between the two prices, divide by the original price, and multiply by 100. Try this method to see that you get the SAME answer.

A bag of candy has 200 pieces when opened. After eating some, there are 146 left. What is the percent decrease?

None of the other answers.

Explanation

Find the amount of decrease, divide it by the starting number, and multiply by 100 to convert to a percentage.

$\frac{54}{200}=.27$

A 27% decrease.

Your weekly allowance went from $40 to $30 a week. Find the percent decrease in your allowance.

Explanation

To find percent decrease, we use the following formula:

$\text{percent decrease} = \frac{\text{original price - new price}}{\text{original price}} \cdot 100$

Using the information given, we know the following:

$\text{original price} = $40.00$

$\text{new price} = $30.00$

so we can substitute these values into the formula. We get

$\text{percent decrease} = \frac{$40.00 - $30.00}{$40.00} \cdot 100$

$\text{percent decrease} = \frac{$10.00}{$40.00} \cdot 100$

$\text{percent decrease} = 0.25 \cdot 100$

$\text{percent decrease} = 25%$

Therefore, the percent decrease in your allowance is .

In 1983 there were an estimated 6,000 snow leopards in the world, but now scientists believe there are only around 3,500. By what percent has the snow leopard population declined since 1983? Round your answer to the nearest tenth of a percent.

$\small 41.7 %$

$\small 71.4 %$

$\small 7.1 %$

$\small 2.4%$

$\small 58.3 %$

Explanation

To figure out the percent change, we want to figure out the amount that the population changed. We can do this by subtracting:

$\small 6,000 - 3,500 = 2,500$

Now we want to figure out what percent that change was of the original. In other words, 2,500 is what percent of 6,000. We can write that as a solvable equation knowing that "of" means multiply:

$\small 2,500 = \frac{x}{100}*6,000$ divide both sides by 6,000

$\small 0.417\approx \frac{x}{100}$ multiply by 100 to convert this decimal into a percentage

$\small 41.7 % = x$

What is the percent decrease from $\small 312$ to $\small 170$ ?

$\small \approx46%$

$\small \approx488%$

$\small \approx48%$

$\small \approx25%$

Explanation

To find the percent change of two numbers, you use the formula:

$\small \frac{difference}{original}\times 100$ .

This formula in the context of this question:

$\small \small \frac{312-170}{312}\times100 = \frac{142}{312}\times 100 = \frac{71}{156}\times 100 \approx45.5%$ .

Thus, now know that if we subtract about forty six percent of the original number from the original number, we would get the second number. We have about a forty six percent decrease.

Paul wanted to sell his car last year. At the time, he was fairly certain that his car was worth $15000. 1 year later, Paul has finally gotten around to selling his car. Unfortunately, due to depreciation in value, the car is only worth $12000. By what percent, did Paul’s car decrease in value?

Explanation

Let represent the original value of Paul's car (its value 1 year ago) and represent the new value of Paul's car (its value today). Using these variables, we can calculate the percent decrease in the car's value with the following expression:

$\left(\frac{N-O}{O}\right)*100$

Plug in the appropriate values into this expression.

$\left(\frac{12000-15000}{15000}\right)*100$

Paul's car lost 20% of its value in 1 year.

A book was originally priced at $12. It was put on sale for $8. To the nearest percent, by what percentage was its price marked down?

Explanation

This problem is a simple percent chage problem. The absoluge change in price was . Relative to the original price, it was $\frac{4}{12}$ , which is or .

In 2013, the population of a city was 390,113 people. The same city had a population of 501,662 people in 1999. By what percent did the population of the city decrease during that time period? Round to the nearest tenth of a percent.

$\small 22.2 %$

$\small 2.22 %$

$\small 77.8 %$

$\small 28.6 %$

$\small 11.1 %$

Explanation

To figure out the percent change, we want to figure out the amount that the population changed. We can do this by subtracting:

$\small 501,662 - 390,113 = 111,549$

Now we want to figure out what percent that change was of the original. In other words, 111,549 is what percent of 501,662. We can write that as a solvable equation knowing that "of" means multiply:

$\small 111,549 = \frac{x}{100}*501,662$ divide both sides by 501,662

$\small 0.222 \approx \frac{x}{100}$ multiply by 100 to convert this decimal into a percentage

$\small 22.2 % = x$

Between January 2nd and February 15th, the number of Christmas trees in windows on Macalaster Lane decreased by . If of the houses originally displayed trees, what percentage of houses still have trees on February 15th?

$\small 10.5 %$

$\small 59.5 %$

$\small 0.105 %$

$\small 0.595 %$

$\small 25.5 %$

Explanation

If the amount of houses decreased by 85%, that means the amount that remain is 100% - 85%, or 15%. We want to find 15% of 70%. Since we're leaving our answer as a percentage, we can just leave 70% as 70, and convert 15% to 0.15 and multiply:

$\small 70*0.15= 10.5$ .

This means our answer is 10.5%.

How to find the percent of decrease

Help Questions

Explanation

Explanation

Explanation

Explanation

Explanation

Explanation

Explanation

Explanation

Explanation

Explanation