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question:Square (ABCD) with side length 2 is inscribed in a circle. Using each side of the square as a diameter, semicircular arcs are drawn. The area of the shaded region outside the circle and inside the semicircles is: (A) (pi) (B) 4 (C) (2pi 2) (D) (pi + 1) (E) (2pi 4)

answer:To find the shaded area outside the circle but inside the semicircles, we need to proceed with the following steps: 1. **Determine the properties of the square**: - The side length of the square ( AB = 2 ). - The diagonal of the square ( AC ) can be calculated using the Pythagorean theorem: [ AC = sqrt{AB^2 + BC^2} = sqrt{2^2 + 2^2} = sqrt{4 + 4} = sqrt{8} = 2sqrt{2} ] 2. **Calculate the area of the circle**: - The diagonal of the square is the diameter of the circle inscribed around the square: [ text{Diameter of the circle} = 2sqrt{2} ] - The radius of the circle is: [ text{Radius} = frac{2sqrt{2}}{2} = sqrt{2} ] - The area of the circle is: [ text{Area of the circle} = pi (sqrt{2})^2 = 2pi ] 3. **Calculate the area of the square**: - The area of the square ( ABCD ) is: [ text{Area of the square} = 2 times 2 = 4 ] 4. **Determine the area outside the square but inside the circle**: - The area outside the square but inside the circle is: [ 2pi - 4 ] 5. **Calculate the area of each semicircle**: - Each side of the square is used as the diameter of a semicircle, hence the radius of each semicircle is: [ text{Radius of each semicircle} = frac{2}{2} = 1 ] - The area of each semicircle is: [ text{Area of each semicircle} = frac{1}{2} pi (1^2) = frac{1}{2} pi ] - The total area of the four semicircles is: [ 4 times frac{1}{2} pi = 2 pi ] 6. **Determine the shaded region**: - The shaded region is the area covered by semicircles not overlapped by the circle: [ text{Shaded area} = 2pi - (2pi - 4) = 2pi - 2pi + 4 = 4 ] # Conclusion The area of the shaded region outside the circle and inside the semicircles is [ boxed{4} ]

question:Lisa has decided to replace her old cutlery. As she is going through the cupboards, she sees the spoons from when each of her 4 children were babies as well as 2 decorative spoons she created. She doesn't want to get rid of any of these so she adds them to her new set of cutlery. The new set of cutlery has 10 large spoons and some teaspoons. Each of her children had 3 spoons when they were babies. Lisa now has 39 spoons. How many teaspoons are in the new set of cutlery?

answer:Lisa has kept 4 children's spoons and 2 decorative spoons, which adds up to: 4 children x 3 spoons each = 12 spoons 12 spoons (children's) + 2 spoons (decorative) = 14 spoons She has a new set of cutlery with 10 large spoons. So, the total number of spoons she has now is: 10 large spoons (new set) + 14 spoons (kept) = 24 spoons Lisa has a total of 39 spoons now. To find out how many teaspoons are in the new set of cutlery, we subtract the 24 spoons we already accounted for from the total: 39 spoons (total) - 24 spoons (accounted for) = 15 teaspoons So, there are boxed{15} teaspoons in the new set of cutlery.

question:Lorenzo put some full cans of thumbtacks into his pocket and went off to work at the corkboard factory. He placed one thumbtack from each can into every board tested. At the end of the day, he had tested 120 boards and had 30 tacks remaining in each can. The total combined number of thumbtacks from the full cans was 450. How many cans of thumbtacks did Lorenzo have?

answer:Let's denote the number of cans Lorenzo had as ( c ). Each can contributed one thumbtack to each of the 120 boards, so each can initially had ( 120 + 30 ) thumbtacks because there were 30 left in each can at the end of the day. So, each can had ( 150 ) thumbtacks at the beginning of the day. The total number of thumbtacks from all the cans was 450, so we can set up the equation: ( c times 150 = 450 ) Now, we solve for ( c ): ( c = frac{450}{150} ) ( c = 3 ) Lorenzo had boxed{3} cans of thumbtacks.

question:Juan, Carlos, Ana, and Manu take turns flipping a coin in their respective order. The first one to flip heads wins. What is the probability that Manu will win if Manu needs to flip two consecutive heads to win? Express your answer as a common fraction.

answer:For Manu to win, he must first flip two consecutive heads when his turn comes, and none of the previous players (Juan, Carlos, Ana) should have flipped heads. The probability of not flipping heads in one turn is frac{1}{2}. Manu needs to flip two consecutive heads, which has a probability of left(frac{1}{2}right)^2 = frac{1}{4}. - **Probability for Manu to win on his first opportunity** (after Juan, Carlos, Ana, all tails, and then two heads by Manu): [ left(frac{1}{2}right)^3 cdot frac{1}{4} = frac{1}{32}. ] - **Probability for Manu to win on his second opportunity** (another full cycle of tails followed by two heads by Manu): [ left(frac{1}{2}right)^7 cdot frac{1}{4} = frac{1}{512}. ] - **Continuing this pattern**, the probability that Manu wins on his nth turn follows: [ left(frac{1}{2}right)^{4n} cdot frac{1}{4}. ] - **Summing these probabilities** as a geometric series: [ sum_{n=1}^{infty} frac{1}{32} left(frac{1}{16}right)^{n-1} = frac{frac{1}{32}}{1-frac{1}{16}} = frac{frac{1}{32}}{frac{15}{16}} = frac{1}{30}. ] The probability that Manu will win under these new conditions is: [ boxed{frac{1}{30}}. ]

Released under the DeepMind License.

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