Apple claims that with a fully charged battery, users of its iPhone 11 can stream video up to 10 hours. The minimum battery life for streaming video is 7.5 hours. Assume that for a randomly selected...

Apple claims that with a fully charged battery, users of its iPhone 11 can stream video up to 10 hours. The minimum battery life for streaming video is 7.5 hours. Assume that for a randomly selected iPhone 11, battery life is
uniformly
distributed between 7.5 and 10 hours. The density function of this uniform probability distribution is given in the figure below.

For values of battery life between 7.5 and 10 hours, the density is 0.4. For all other values of battery life, the density is 0.

In the figure above, indicate the probability that a randomly selected iPhone 11 has a battery life between 9 and 10 hours. What is the value of this probability?