Since you're looking at 2 standard deviations from the mean, you follow the 66 95 rule which says 95 % of the data is within 2 standard deviations. however you just need half of that since the other half is on the other side of the data meaning it last longer than 7 days. So 2.5% is the answer.
1/5 of an hour is 12 minutes. 60 seconds x 12 minutes= 720 seconds
No. Mass is the measurement of how much matter is in something.
Take neutron stars for example; smaller than our sun but has more mass. Because of density.
