It looks a bit complicated at first glance but it's quite simple.
Her initial pick has 1/6 (~0.16) chance to be a normal egg. This means the rest of the eggs have 5/6 chances to be normal. When it is revelead that one of the 5 eggs is boiled, it's chance to be normal becomes zero. Thus, the 5/6 chance to be normal is now for the group of eggs 2,3,4 and 5. By changing her choice, she now has 1/4*5/6 (~0.2) chance to get the normal egg - higher than the initial 0.16 .
She doesn't want that so she should carry on with her initial choice.
Her initial pick has 1/6 (~0.16) chance to be a normal egg. This means the rest of the eggs have 5/6 chances to be normal. When it is revelead that one of the 5 eggs is boiled, it's chance to be normal becomes zero. Thus, the 5/6 chance to be normal is now for the group of eggs 2,3,4 and 5. By changing her choice, she now has 1/4*5/6 (~0.2) chance to get the normal egg - higher than the initial 0.16 .
She doesn't want that so she should carry on with her initial choice.




