Test Your Comprehension And Understanding Of Percentages

Explanation
The percent increase in Mary's height can be found by taking the difference between her final height (130 cm) and her initial height (61 cm), dividing it by her initial height, and then multiplying by 100. Therefore, the percent increase is (130 - 61) / 61 * 100 = 113.12%.

Explanation
To find the percentage, we divide the given number (30) by the total number (20) and multiply by 100. In this case, 30 divided by 20 is 1.5, and when multiplied by 100, it gives 150%. Therefore, 30 is 150% of 20.

Explanation
To find 35% of 80, we can multiply 80 by 0.35. This gives us 28, which is the correct answer.

Explanation
To find 45% of a number, we can multiply the number by 0.45. In this case, if we let "x" represent the number, we have the equation 0.45x = 9. Dividing both sides of the equation by 0.45, we find that x = 20. Therefore, 45% of 20 is equal to 9.

Explanation
The percent increase can be calculated by finding the difference between the new price and the original price, dividing it by the original price, and then multiplying by 100. In this case, the difference between the new price (81 cents) and the original price (75 cents) is 6 cents. Dividing 6 by 75 and multiplying by 100 gives us 8%, which represents the percent increase.

Explanation
The percent change can be calculated by finding the difference between the selling price and the buying price, dividing it by the buying price, and then multiplying by 100. In this case, the difference between the selling price ($75) and the buying price ($40) is $35. Dividing $35 by $40 gives 0.875, which when multiplied by 100 gives 87.5%. This represents a 87.5% increase in price from the buying price to the selling price.

Explanation
The item is originally priced at $55 and is marked 25% off. To find the sale price, we can calculate 25% of $55, which is $13.75. Subtracting $13.75 from $55 gives us the sale price of $41.25.

Explanation
The percent change is calculated by finding the difference between the original price and the new price, dividing that difference by the original price, and then multiplying by 100. In this case, the original price is $425 and the new price is $318.75. The difference between these two prices is $425 - $318.75 = $106.25. Dividing this difference by the original price, $106.25 / $425 = 0.25. Multiplying by 100 gives us 0.25 * 100 = 25%. Therefore, the percent change is 25%.

Explanation
The percentage weight loss can be calculated by finding the difference between the initial weight and the final weight, dividing it by the initial weight, and then multiplying by 100. In this case, the difference between 125 pounds and 110 pounds is 15 pounds. Dividing 15 pounds by 125 pounds gives 0.12, and multiplying by 100 gives 12%. Therefore, the correct answer is 12%.

Explanation
The percent change can be calculated by finding the difference between the new and old values, dividing it by the old value, and then multiplying by 100. In this case, the difference between $8.00 and $6.00 is $2.00. Dividing $2.00 by $6.00 gives 0.3333. Multiplying 0.3333 by 100 gives 33.33%. Therefore, the percent change is 33.33%.

Explanation
Sandra bought the stock for $30 and sold it for $36. To find the profit percentage, we need to calculate the difference between the selling price and the buying price, which is $36 - $30 = $6. Then, we divide this profit by the buying price and multiply by 100 to get the percentage: ($6 / $30) * 100 = 20%. Therefore, Sandra made a profit of 20%.

Explanation
The reduction in price from $24.50 to $17.95 can be calculated by finding the difference between the two prices, which is $6.55. To find the percentage reduction, divide this difference by the original price ($24.50) and multiply by 100. This calculation gives a reduction of approximately 26.7%.

Explanation
The percent change in salary can be calculated by finding the difference between the new salary and the old salary, dividing it by the old salary, and then multiplying by 100. In this case, the difference between $45,000 and $33,000 is $12,000. Dividing this by $33,000 gives a result of approximately 0.3636. Multiplying by 100 gives a percent change of approximately 36.36%, which is rounded to 36.3%. Therefore, the correct answer is 36.3%.

Explanation
The original price of the shirt was $20 and it decreased to $15. To find the percent decrease, we need to calculate the difference between the original price and the decreased price, which is $20 - $15 = $5. Then, we divide this difference by the original price, $5/$20 = 0.25. Finally, we multiply this result by 100 to get the percentage, 0.25 * 100 = 25%. Therefore, the percent decrease of the price of this shirt is 25%.

Explanation
The second decrease was larger in percentage terms. The price decreased by $20 from $100 to $80, which is a decrease of 20%. In comparison, the first decrease was from $120 to $100, which is a decrease of $20 but only 16.67% of the original price.