help, please... i am so lost. Even if you can just send me a link to a calc where I can input values?

A rechargable laptop battery lasts for a mean duration of = 5.1 hours with = 1.2 hours. If 15 batteries are charged and tested, find the probability that their mean duration is less than 4.7 hours.

Question 6 options:

0.3707

0.9015

0.0985

0.6293

A rechargable laptop battery lasts for a mean duration of = 5.5 hours with = 1.3 hours. If a battery is tested, find the probability that the mean duration is less than 5.1 hours.

Question 7 options:

0.3783

0.1170

0.8830

0.6217