In mathematical notation, ∑ means summation. So wherever you see the symbol, you have to sum over all elements in the set. Let's solve the question.
a. ∑m means, to sum all elements in the set m: ∑m = 12 + 15 + 20 + 30 = 77
b. ∑
means to sum all elements in the set f as the square of the elements f = 
c. ∑mf means to sum all elements as the product of the elements of m and f = (12×5) + (15×9) + (20
10) + (30×16) = 875
d. ∑
means to sum all elements as the product of the square of m and f = 
A. First, divide 1675 by 100 to find 1% of it.
1675 / 100 = 16.75
Then, multiply 16.75 by 4.6 to get 4.6%.
16.75 x 4.6 = 77.05
77.05 is the interest for one year.
Multiply it by 4 to get the interest for 4 years.
77.05 x 4 = 308.20
The interest earned is $308.20.
B. Add the interest to the original balance to get the total.
308.20 + 1675 = 1983.20
The balance of the account is $1983.20 after 4 years.
Hope this help!
Always- their slopes are always opposite reciprocals of each other
I'll do it with a fraction, so let's say 15/45. 15 of the cards are baseball cards, 30 of them are other cards. I would say 15/45, because 45 is the total amount of the cards he has. Only 15 are BASEBALL cards, so it would make sense to say he has a 15/45 chance to pull a baseball card.
