An assembly-line machine turns out washers with the following thicknesses (in millimeters). find the mean and standard deviation of the thicknesses.
1.42, 1.83, 1.43, 1.87, 1.22, 1.44, 1.72, 1.91, 1.42, 1.87, 1.42, 1.99, 1.27, 1.94, 1.67, 1.22

Afamily has two cars. the first car has a fuel efficiency of 25 miles per gallon of gas and the second has a fuel efficiency of 15 miles per gallon of gas. during one particular week, the two cars went a combined total of 1025 miles, for a total gas consumption of 55 gallons. how many gallons were consumed by each of the two cars that week?