Amath class has 7 girls and 3 boys in the seventh grade and 3 girls and 9 boys in the eighth grade. the teacher randomly selects a seventh grader and an eighth grader from the class for a competition. what is the probability that the students she selects are both girls?

What could explain what happened when the time was equal to 120 minutes

The distance of a chord from the centre of a circle is 12cm and the lenght of the chord is 10cm. find the radius of the circle

In a test for esp (extrasensory perception), a subject is told that cards only the experimenter can see contain either a star, a circle, a wave, or a square. as the experimenter looks at each of 20 cards in turn, the subject names the shape on the card. a subject who is just guessing has probability 0.25 of guessing correctly on each card. a. the count of correct guesses in 20 cards has a binomial distribution. what are n and p? b. what is the mean number of correct guesses in 20 cards for subjects who are just guessing? c. what is the probability of exactly 5 correct guesses in 20 cards if a subject is just guessing?