Final answer:
The cooking time for a 13 kg turkey can be roughly estimated by using the rule of 15 minutes per pound at 325 degrees Fahrenheit, leading to an estimated cooking time of approximately 7.15 hours, but factors like oven calibration and turkey shape can affect this time.
Step-by-step explanation:
When determining how long it will take to cook a 13 kg turkey, based on the provided information that a 7 kg turkey takes about 2.5 hours to cook, we need to consider the concept of heat diffusion. When cooking, the time it takes for the turkey to cook is related to the diffusion process of heat throughout the turkey's mass. Although not linear, we can use the information from your mom's experience as a starting point.
A common rule for roasting a turkey in an oven is approximately 15 minutes per pound at 325 degrees Fahrenheit. A 13 kg (approximately 28.6 pounds) turkey would then require around 7.15 hours, which is 429 minutes or about 7.2 hours. However, cooking times can vary based on a number of factors including oven calibration, whether the turkey is stuffed, and the shape and thickness of the turkey.