The radioactive substance neptunium -139 decays to 72.85% of its original amount after 28 hours. How long (to the nearest hour) would it take for 37% of the original neptunium to be present?
?
__________ hours
Fill in the blank(s) with the appropriate word(s).
88
Mathematics
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Solve the problem.A game involves choosing 5 different numbers from the numbers 1 through 13.In how many ways can this be done?
A. 154,440 B. 1295 C. 1267 D. 1287
Mathematics
Solve the equation by making an appropriate substitution.x4 - 20x2 - 125 = 0
A. {- 
, 
, -5i, 5i}
B. {5, i
}
C. {-25, 5}
D. {-5, 5, -i
, i
}
Mathematics
Simplify the expression.
A. 
B. - 
C. 
D. 
Mathematics
Use the Gauss-Jordan method to find A-1, if it exists.A = 
A. 
B. 
C. 
D. Does not exist
Mathematics