Melanie saves $20 every month in her savings account. she withdrew $60 one time to go shopping. she now has $280 in her account. write and solve an equation to determine how many months she has been saving. define the variable write the equation and solve. write your answer in sentence.

Aproduction manager test 10 toothbrushes and finds that their mean lifetime is 450 hours. she then design sales package of this type of toothbrush. it states that the customers can expect the toothbrush to last approximately 460 hours. this is an example of what phase of inferential statistics