There are 9 students in a class: 5 boys and 4 girls.
1 answer:
Answer:
5/126
Step-by-step explanation:
Let's go through this scenario step-by-step. At the beginning, we have a 5/9 possibility of picking a boy - 5 boys out of 9 students. If we pick 1 boy, we now have 4 boys out of 8 students we could potentially pick, giving us a 4/8 or 1/2 chance of picking a second boy after the 1st. For the third boy, we have 3 out of 7 remaining students, giving us a 3/7 chance of picking a third after the first two, and for the fourth boy, we 2 possibilities out of 6, giving us a 2/6 or 1/3 chance of picking the 4 boys.
To find the total probability, we can multiply all of these individual ones together:
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<h3>Answer: 110 square miles</h3>
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Explanation:
There are a few ways to do this.
One method involves drawing a horizontal line to form three rectangles as show below. Note the labels A,B,C.
- Rectangle A in the upper left corner has area of base*height = 6*7 = 42 square miles. I'll let A = 42 since we'll use it later.
- Rectangle B is 20 miles across horizontally (base) and 2 miles tall vertically (height). The 2 miles is from 9-7 = 2. The area of rectangle B is 20*2 = 40 square miles. Let B = 40.
- Then finally, C = 28 because rectangle C is 4 miles across and 7 miles tall, so 4*7 = 28.
Add up those three sub areas found: A+B+C = 42+40+28 = 110 square miles
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There are other methods you could do. A second method is to draw two vertical lines to form 3 other rectangles, then add up the sub areas to get 110.
A third method is to draw a horizontal line across the top to form one large rectangle (20 mi by 9 mi) and subtract off the area of the 7 mi by 10 mi inner rectangle (the empty space), so you'd say 20*9 - 7*10 = 180-70 = 110