If each mark on the circle in the model above stands for approximately one day, in about how many days will the moon be in its last quarter phase?​​

7 days.

Explanation:

In 7 days the moon will be in its last quarter phase. In the last quarter phase, the half part of the moon is illuminated and the other half is hide in darkness. The illumination of the sides of the moon provide information about the dates of the month. Last quarter phase is also called third phase of the moon. In this phase, the Moon is in quadrature and has the elongation of 270 degree. It is also the indication that the half cycle of the moon is completed and the other half is started.

most community's take hundreds of years to become stable

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.