Answer:

Step-by-step explanation:
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Answer: 3 copies of 5 tenths = 3*0.5 = 1.5
Step-by-step explanation:
Ok, if we have:
"3 copies of a number B"
This is written as:
3*B
And we have that the number B is "5 tenths"
Now, a tenth is the first digit after the decimal point.
Then 5 tenths = 5*0.1 = 0.5
B = 0.5
3 copies of 5 tenths = 3*0.5 = 1.5
Given:
The sequence is 25, 20, 15, 10, 5.
To find:
The ninth term of the given sequence.
Solution:
We have,
25, 20, 15, 10, 5
It is an AP because the difference between two consecutive terms are same.
Here,
First term (a) = 25
Common difference (d) = 20-25
= -5
The nth terms of an AP is

Where, a is the first term and d is the common difference.
Putting a=25, n=9 and d=-5 to get the 9th term.




Therefore, the ninth term of the given sequence is -15.
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