Please help 1. rubidium has two isotopes, 72.2% rubidium-85, and 27.8% rubidium-87. Calculate the average atomic mass of rubidium. 2. Bromine also has two isotopes: 50.7% is bromine-79 and 49.3% is bromine-81. Can you estimate the average atomic mass of bromine without using a calculator? 3. What is the average atomic mass of fluorine, whose only naturally occurring isotopes has an atomic mass of 19?

Using pert, adam munson was able to determine that the expected project completion time for the construction of a pleasure yacht is 21 months, and the project variance is 4. a) what is the probability that the project will be completed in 17 months? b) what is the probability that the project will be completed in 20 months? c) what is the probability that the project will be completed in 23 months? d) what is the probability that the project will be completed in 25 months? e) what is the due date that yields a 95% chance of completion?

Susie wants to take her friend out for lunch.she wants to spend $9.75 each person. how much will she spend in all.

Which of the following statements are true about the graph of f (x) = 1/4 coz ( x + π/3) - 1? select two of the following that apply.