Percentage Calculations and Circle Circumference

Mrs. Groovy Groves guides students through lesson six of unit four, focusing on understanding and calculating percent increases and decreases. The lesson includes drawing diagrams to visualize percent changes, writing these changes as percentages of initial amounts, and graphing relationships between diameter and circumference. The video also covers using fractions in equations to represent relationships, providing a comprehensive understanding of these mathematical concepts.

In a diagram, if X is represented by 4 bars, each 25%, and Y is 75%, what is the percentage change of Y relative to X?

• Y is a 25% increase

• Y is a 25% decrease

• Y is a 50% increase

• Y is a 50% decrease

If a bakery used 50% more flour this month compared to last month, what percentage does this month's usage represent of last month's?

• 200%

• 50%

• 150%

• 100%

This year, there were 25% fewer sunny days than last year. What percentage of last year's sunny days does this year represent?

• 100%

• 50%

• 125%

• 75%

If the runner's time to complete a marathon was 10% less than the last marathon, what percentage of the last marathon's time did the runner achieve?

• 80%

• 110%

• 100%

• 90%

If last month is considered 100% and this month saw a 50% increase in houses sold, what percentage does this month's sales represent?

• 100%

• 150%

• 200%

• 50%

If the diameter of a circle is 2, what is the approximate circumference using the formula C = πD?

• 12.56

• 6.28

• 9.42

• 3.14

When the diameter of a circle is 3, what is the approximate circumference?

• 3.14

• 12.56

• 9.42

• 6.28

If the diameter of a circle is 4, what is the approximate circumference?

• 12.57

• 9.42

• 6.28

• 15.70

If Priya bought X grams of flour and Claire bought 3/8 more than that, what is the relationship between Claire's and Priya's flour amounts?

• Y = X + 3/8

• Y = 11/8 X

• Y = X - 3/8

• Y = 8/8 X

What is the equivalent expression for Y = X + 3/8X?

• Y = 11/8X

• Y = 5/8X

• Y = 8/8X

• Y = 3/8X