I prefer to use compatible numbers because by using this method it is easier to make a sum mentally. This is true because compatible numbers are close in value to the actual numbers. For a better understanding, let's take an example:
Suppose you have two numbers, namely 640 and 40. These two numbers are compatible for division because:
64 ÷ 4 = 16
So, we have used mental arithmetic to solve a more complex problem.
Answer:
- 33 1/3 liters of 30%
- 16 2/3 liters of 45%
Step-by-step explanation:
Let x represent the liters of 45% solution needed. Then the amount of HCl in the mix is ...
0.45x +0.30(50 -x) = 0.35(50)
0.15x = 0.05(50) . . . . . simplify, subtract 0.30(50)
x = (0.05/0.15)(50) = 50/3 = 16 2/3 . . . liters of 45% HCl
33 1/3 liters of 30% and 16 2/3 liters of 45% HCl are needed.
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<em>Comment on the solution</em>
You may notice that the general solution to a mixture problem of this sort is that the fraction of the mix that is the highest contributor is ...
(mix % - low %) / (high % - low %) = (.35 -.30) / (.45 -.30) = .05/.15 = 1/3
Answer:
36
Step-by-step explanation:
Since f(x) varies directly with x, f(x) can be expressed alternatively as \[f(x) = k * x\] where k is a constant value.
Given that f(x) is 72 when the value of x is 6.
This implies, \[72 = k * 6\]
Simplifying and rearranging the equation to find the value of k:
k = \frac{72}{6}
Hence k = 12
Or, \[f(x) = 12 * x\]
When x = 3, \[f(x) = 12 *3 \]
Or in other words, the value of f(x) when x=3 is 36
