SOLUTION: If r varies jointly as s and t, and r=90 when s=8 and t=15, find r when s=7 and t=12
Algebra
->
Sequences-and-series
-> SOLUTION: If r varies jointly as s and t, and r=90 when s=8 and t=15, find r when s=7 and t=12
Log On
Algebra: Sequences of numbers, series and how to sum them
Section
Solvers
Solvers
Lessons
Lessons
Answers archive
Answers
Click here to see ALL problems on Sequences-and-series
Question 1091588
:
If r varies jointly as s and t, and r=90 when s=8 and t=15, find r when s=7 and t=12
Answer by
Boreal(15235)
(
Show Source
):
You can
put this solution on YOUR website!
r=kst, solve for k
90=k*8*15=120k
k=3/4
now use that value of k
r=0.75*7*12=63