1. We assume, that the number 3000 is 100% - because it's the output value of the task.
<span>2. We assume, that x is the value we are looking for. </span>
<span>3. If 100% equals 3000, so we can write it down as 100%=3000. </span>
<span>4. We know, that x% equals 600 of the output value, so we can write it down as x%=600. </span>
5. Now we have two simple equations:
1) 100%=3000
2) x%=600
where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:
100%/x%=3000/600
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.
7. Solution for 600 is what percent of 3000
100%/x%=3000/600
<span>(100/x)*x=(3000/600)*x - </span>we multiply both sides of the equation by x
<span>100=5*x - </span>we divide both sides of the equation by (5) to get x
<span>100/5=x </span>
<span>20=x </span>
<span>x=20
So 600 is 20% of 3000</span>
46.2 dollars for the large necklaces and 14 dollars and seventy cents for the small necklaces therefore she will earn $60.9
Answer:
8
Step-by-step Explanation:
Step 1. Divide 1200 by 300:
1200 ÷ 300 = 4
Step 2. Multiply 4 by 2:
4 * 2 = 8
This is a refreshing question!
We are given that
f(r)=ar+b, and
Sum f(r) =125 for r=1 to 5
Sum f(r) = 475 for r=1 to 10.
and we know, using Gauss's method, that
G(n)=sum (1,2,3.....n) = n(n+1)/2 or
G(n)=n(n+1)/2
Sum f(r) =125 for r=1 to 5
=>
sum=a(sum of 1 to 5) + 5b => G(5)a+5b=125 [G(5)=15]
15a+5b=125 ...................................................(1)
Similarly, Sum f(r) = 475 for r=1 to 10 => G(10)a+5b=475 [G(10)=55]
=>
55a+10b=475.................................................(2)
Solve system of equations (1) and (2)
(2)-2(1)
55-2(15)a=475-2(125) => 25a=225 =>
a=9
Substitute a=9 in 1 => 15(9)+5b=125 => 5b=-10
b=-2
Substitute a and b into f(r),
f(r)=9r-2
check: sum f(r), r=1,5 = (9-2)+(18-2)+(27-2)+(36-2)+(45-2)=135-10=125 [good]
We define the sum of f(r) for r=1 to n as
S(n)=sum f(r) for r=1 to n = 9(sum 1,2,3....n)-2n = 9n(n+1)/2-2n = 9G(n)-2n
S(n)=9n(n+1)/2-2n
checks:
S(5)=9(15)-2(5)=135-10=125 [good]
S(10)=9(55)-2(10)=495-20=475 [good]
Hence
(a)
S(n)=sum f(r) for r=1,n
= 9(sum i=1,n)+n(-2)
= 9(n(n+1)/2 -2n
=(9(n^2+n)/2) -2n
(b) sum f(r) for i=8,18
=sum f(r) for i=1,18 - sum f(r) for i=1,7
=S(18)-S(7)
=(9(18^2-18)/2-2(18))-(9(7^2-7)/2-2(7))
=1503-238
=1265
