Can someone help me with this

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

Karen is financing $291,875 to purchase a house. she obtained a 15/5 balloon mortgage at 5.35%. what will her balloon payment be? a. $220,089.34 b. $219,112.46 c. $246,181.39 d. $230,834.98

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