Help pls, i don’t get it

Aquantity with an initial value of 3900 decays exponentially at a rate of 35% every hour. what is the value of the quantity after 0.5 days, to the nearest hundredth?

Abag contains 4 red, 7 blue and 5 yellow marbles. event a is defined as drawing a yellow marble on the first draw and event b is defined as drawing a blue marble on the second draw. if two marbles are drawn from the bag, one after the other and not replaced, what is p(b|a) expressed in simplest form? a. 7/16 b. 7/15 c. 14/16 d. 14/15

Fa bus driver leaves her first stop by 7: 00 a.m., her route will take less than 37 minutes. if she leaves after 7: 00 a.m., she estimates that the same route will take no less than 42 minutes. which inequality represents the time it takes to drive the route, r?