Answer:
8750
Step-by-step explanation:
Since the random sample contained 125 out of 500 people who voted for the dog park that is about 25%. since 25% of 500 is 125. If we scale that up to 25% of 3500 it would be 8750 people.
19+x/2=4
multiply 2 on both sides
19+x=4 times 2
19+x=8
subtract 19 on each side
x=8-19
subtract
x=-11
Answer:
<h2>The specific heat of the metal is 0.274951 calories/gram-degree C.</h2>
Step-by-step explanation:
Let, the specific heat of the container is x calories/gram-degree C.
The container and water gains (18 - 15) = 3 degrees C.
Hence, the transfer of heat is 
.
The metal, which is dropped in the water, losses (164 - 18)= 144 degrees C.
Hence, the transfer of heat is 
.
As per the given conditions,
.
Assume that the amount needed from the 5% solution is x and that the amount needed from the 65% solution is y.
We are given that, the final solution should be 42 ml, this means that:
x + y = 42 ...........> equation I
This can also be written as:
x = 42-y .......> equation II
We are also given that the final concentration should be 45%, this means that:
5% x + 65% y = 45% (x+y)
0.05x + 0.65y = 0.45(x+y)
We have x+y = 42 from equation I, therefore:
0.05x + 0.65y = 0.45(42)
0.05x + 0.65y = 18.9 .........> equation III
Substitute with equation II in equation III as follows:
0.05x + 0.65y = 18.9
0.05(42-y) + 0.65y = 18.9
2.1 - 0.05y + 0.65y = 18.9
0.6y = 18.9 - 2.1
0.6y = 16.8
y = 28 ml
Substitute with y in equation II to get x as follows:
x = 42-y
x = 42 - 28
x = 14 ml
Based on the above calculations:
amount of 5% solution = x = 14 ml
amount of 65% solution = y = 28 ml
The correct choice is:
The teacher will need 14 mL of the 5% solution and 28 mL of the 65% solution.
