OP...Put your mind at ease:
Manufacturers have Chemists that have
not only formulated these concentrated
products ("stock solutions"), but have
taken out most of the dilution guesswork
by also including the calculated dilution
ratios for the end users' convenience.
Note:
The formula for determining the amount
of a "stock solution" (at a known strength)
that's needed to make a diluted solution
(at the desired amount and strength) is:
Q1 X C1 = Q2 X C2
Where:
Q = quantity
C = concentrate
(quantity1) X (concentration1) =
(quantity2) X (concentration2)
All that's left is to: plug in the
numbers; and, solve: by the
inverse proportion methodology.
Bob