Math Proportionality and Cost Flashcard

Front

What is proportionality in mathematics?

Back

Proportionality refers to the relationship between two quantities where their ratio remains constant. If one quantity increases, the other increases in a consistent manner.

Front

How do you calculate a percentage tip?

Back

To calculate a percentage tip, multiply the total bill amount by the tip percentage (as a decimal). For example, for a $25 bill with a 20% tip: $25 x 0.20 = $5.

Front

What is percent error?

Back

Percent error is a measure of how inaccurate a measurement is, compared to the true value. It is calculated as: |(Estimated Value - True Value)| / True Value x 100%.

Front

How do you convert a percentage to a fraction?

Back

To convert a percentage to a fraction, divide the percentage by 100 and simplify. For example, 37.5% = 37.5/100 = 3/8.

Front

What does it mean for two ratios to be proportional?

Back

Two ratios are proportional if they can be expressed as equivalent fractions. For example, 4/5 and 10/30 are not proportional because 4/5 does not equal 1/3.

Front

What is the formula for calculating the total cost after a tip?

Back

Total Cost = Original Bill + (Original Bill x Tip Percentage). For example, if the bill is $20 and the tip is 15%, Total Cost = $20 + ($20 x 0.15) = $23.

Front

How do you find the difference in earnings?

Back

To find the difference in earnings, subtract the lower amount from the higher amount. For example, if one earns $500 and another earns $558.80, the difference is $558.80 - $500 = $58.80.

Front

What is the relationship between fractions and percentages?

Back

Fractions can be converted to percentages by multiplying the fraction by 100. For example, 1/4 = 0.25 x 100 = 25%.

Front

How do you determine if two fractions are proportional?

Back

To determine if two fractions are proportional, cross-multiply and compare the products. If the products are equal, the fractions are proportional.

Front

What is a common mistake when calculating percent error?

Back

A common mistake is not taking the absolute value of the difference between the estimated and true values, which can lead to a negative percent error.