The life of a fully charged cell phone battery is normally distributed with a mean of 12 hours and a standard deviation of half an hour. What percent of batteries last less than 11 hours? ​

One card is dealt from a 52 card deck. find the probability that the dealt card is a 4 or a black 7

Solve -2(4y + 6) = 52. 5 -5 8 -8 and !

Apublic library wants to place 4 magazines and 9 books on each display shelf. the expression 4s+9s represents the total number of items that will be displayed on s shelves. simplify the expression