I imagine that not everyone that visited Becky’s Store spent a lot of time and money there. If she surveys only those that did, this is not a representative sample because she is leaving out other customers. She would have no one in her sample that represents customers who spent a lot of time but no money, or little time and no money or even little time and a lot of money. These are just some examples but clearly her sample is biased.
Well I'm not sure what the answer would be since I'm not that smart but I did get the answer of 90, I did this by dividing 72 by 80 which equals .9 and I multiplied that by 100 and got 90.
