Discuss how the calibration curve, using known standards, was used to determine the percent contaminants in the sand sample. be sure to comment on the mathematical model and r2 obtained from the calibration curve.

Nick and nora are married and have three children in college. they have an adjusted gross income of 47,400. if their standard deduction is 12,600 itemized deductions are 14,200 and they get an exemption of 4000 for each adult and each dependent what is their taxable income

2people are trying different phones to see which one has the better talk time. chatlong has an average of 18 hours with a standard deviation of 2 hours and talk-a-lot has an average of 20 hours with a standard deviation of 3. the two people who tested their phones both got 20 hours of use on their phones. for the z-scores i got 1 for the chatlong company and 0 for talk-a-lot. what is the percentile for each z-score?

Present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?