Four vulgar fractions that are greater than 1/2 but smaller than 3/4j

Three coins are flipped. what is the probability that there will be at least two tails?

Both the red and blue line segments stretch from the center of the circle to a point on the circle. the length of the blue segment is 5. how long is the red line segment?

Lisa has three classes that each last 50 minutes. what is the total number of minutes of the three classes