The sales data from the past two months of a frozen yogurt shop are approximately normal. The mean daily sales for the first month was $200 with a standard deviation of $30. On the 15th of the first month, the shop sold $245 of yogurt. The mean daily sales for the second month was $220 with a standard deviation of $50. On the 15th of the second month, the shop sold $270 of yogurt. Which month had a higher z-score for sales on the 15th, and what is the value of that z-score