Answer:
138
Step-by-step explanation:
4× 4 3/10= 4×43/10= 86/5= 17 1/5
Answer:
We have to add 1.86 L of water to make the solution 7% saline.
Step-by-step explanation:
The concentration of a saline solution is given by
C(x) = 
where x represents the amount of water used to dilute the solution.
We have to find how much water must be added to obtain a solution that is 7% saline.
If we see the equation we notice that as we add the value of x, the concentration of the solution decreases.
Here C(x) = 0.07
0.07 = 
Rearranging,
1 + x = 
1 + x = 2.86
x = 1.86 L
We have to add 1.86 L of water to make the solution 7% saline.
Answer:
approximately 43 - 44 minutes exact
I'm confused too and I'm supposed to be an expert. I'm not entirely sure what frequency density is. We'll just treat this as a histogram.
Let's assume each five minute interval gives a value equal to or proportional to the number of people that finished in that interval.
From 0 to 50 we have 10 intervals; let's just make this into a table
0-5 0
5-10 40
10-15 40
15-20 30
20-25 30
25-30 25
30-35 25
35-40 25
40-45 25
45-50 15
From 0 to 40 that adds up to
0+40+40+30+30+25+25+25 = 215
From 0 to 50 that's
215+25+15 = 255
The fraction less than 40 is 215/255 = 43/51 ≈ .843
Answer: 84.3%