Please provide complete solutions and answers so that I can fully understand and study well. Also have a readable penmanship, thank you.

0.05 2. Two stores at SM Downtown are selling batteries for cell phones. Store A claims an average battery life of 12 hours while Store B advertises an average of 14 hours. Why would we need to know the standard deviation of the battery life before deciding what brand to buy? Suppose the standard deviation are 1.5 hours for A and 1 hour for B, which battery is more likely to last all day? 3. Suppose that in a casino, a certain slot machine pays out an average of Php 15, with a standard deviation of Php 5,000. Every play of the game costs a gambler Php 20. a. Why is the standard deviation so large? b. If your parent decides to play with this slot machine 5 times, what are the mean and standard deviation of the casino's profit? c. If the gamblers play with this slot machine 1000 times in a day, what are the mean and standard deviation of the casino's profits