China Primary Mathematical Olympiad

To find the total number of animals, we can add the number of sheep, cows, and pigs: 12 + 18 + 24 = 66.

The area of a rectangle is calculated by multiplying its length and width. Therefore, the area of the garden is 10 meters * 8 meters = 80 square meters.

To find the average speed, we divide the total distance traveled by the time taken: 200 kilometers / 4 hours = 50 kilometers per hour.

To find the total amount spent, we can multiply the price of each item by the quantity purchased and then add the results: (2 shirts * $10 per shirt) + (3 pairs of pants * $15 per pair) = $20 + $45 = $80.

To find the probability of selecting a red ball, we divide the number of red balls by the total number of balls: 12 red balls / (12 red balls + 8 blue balls + 6 green balls) = 12/26 = 1/2.

To find the number of acres planted with wheat, we can subtract the acres planted with corn and soybeans from the total acres: 100 acres - (40% of 100 acres + 30% of 100 acres) = 100 acres - (40 acres + 30 acres) = 30 acres.

The perimeter of a rectangle is the sum of the lengths of all four sides. Therefore, the perimeter of the room is 2 * (length + width) = 2 * (6 meters + 4 meters) = 20 meters.

To find the total amount spent, we can multiply the price of each item by the quantity purchased and then add the results: (3 apples * $1 per apple) + (2 oranges * $0.75 per orange) + (4 bananas * $0.50 per banana) = $3 + $1.50 + $2 = $7.75.

To find the time when the second train overtakes the first train, we can calculate the time it takes for the second train to cover the distance between the two trains. The distance between the two trains is equal to the speed of the first train multiplied by the time difference between the two trains. Once we know the distance, we can divide it by the speed of the second train to find the time it takes for the second train to cover that distance.

To find the total number of eggs laid in a week, we can multiply the number of chickens by the number of eggs laid by each chicken per day and then multiply by the number of days in a week: 100 chickens * 1 egg per chicken per day * 7 days = 700 eggs.

The area of a rectangle is calculated by multiplying its length and width. Therefore, the area of the garden is 12 meters * 8 meters = 96 square meters.

To find the average speed, we divide the total distance traveled by the time taken: 300 kilometers / 5 hours = 60 kilometers per hour.

To find the total amount spent, we can multiply the price of each item by the quantity purchased and then add the results: (3 shirts * $10 per shirt) + (2 pairs of pants * $15 per pair) = $30 + $30 = $70.

To find the probability of selecting a blue ball, we divide the number of blue balls by the total number of balls: 10 blue balls / (15 red balls + 10 blue balls + 5 green balls) = 10/30 = 1/3.

To find the number of acres planted with wheat, we can subtract the acres planted with corn and soybeans from the total acres: 120 acres - (40% of 120 acres + 30% of 120 acres) = 120 acres - (48 acres + 36 acres) = 48 acres.