the element born has two stable isotopes. boron-10 has an atomic mass of 10.0129 and a percentage in nature of 19.78% the atomic mass of boron-11 is 11.0093 and its percentage in nature is 80.22% what is the average atomic mass for boron?

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The average hourly earnings for a construction worker is projected to be $24.50 in 2012. jason wants to join the construction work force after he graduates in 2012. his friend tells him that average hourly earnings for construction workers will rise by 2% from 2009 to 2012. based on the data below, assuming that the projected hourly earnings are correct, is jason’s friend’s statement accurate? construction industry - average hourly earnings, 2000-2009 a. his friend’s statement is accurate. the average hourly earnings will increase by 2%. b. his friend’s statement is not accurate. the percent increase will be more than 2% c. his friend’s statement is not accurate. the percent increase will be less than 2% d. his friend’s statement is not accurate. the average hourly earnings will decrease

Olga bought a new skirt that cost $20. sales tax is 5%. how much did olga pay, including sales tax? 7.