Juan makes a measurement in a chemistry laboratory and records the result in his lab report. the standard deviation of students' lab measurements is ? = 10 milligrams. juan repeats the measurement 4 times and records the mean x of his 4 measurements.1. what is the standard deviation of juan's mean result? (that is, if juan kept on making 4 measurements and averaging them, what would be the standard deviation of all his x 's? ) give your answer as a whole number.2. how many times must juan repeat the measurement to reduce the standard deviation of x to 2? (give your answer as a whole number.)3. what is the advantage of reporting the average of several measurements rather than the result of a single measurement? a. the average of several measurements is more likely to be close to the mean than the result of a single measurement. b. the average of several measurements gives an exact result. c. taking several measurements makes the standard deviation larger than that of a single measurement.