Roberto and Sally are busy making cakes for a bake sale. They need to make 35 cakes for the sale. The cooking times of the cakes are independent and normally distributed. Sally makes 19 of the cakes I and Roberto makes 16 of them. Sally's have average cook time of 45 minutes each, with standard deviation of 3 minutes. Roberto's cook, on average, 42 minute each, with standard deviation of 4 minutes. What is the probability I that the average of their 35 baking times is actually between 43 to 44 minutes altogether?