Pg. 977 #70
5
1/5∑ai
I=1

Basically what this means is that you are going to do 1/5(2.9+3.6+4.5+4.9+5.5) The 5 above the symbol means how many numbers you are going to have within the () since you need the average you multify by 1/5 (or divide by 5)

a. 1/5 (2.9+3.6+4.5+4.9+5.5)= 4.28 billion

b. an= .65 (1)+ 2.3 =2.95 an= .65 (2)+ 2.3=3.9 an= .65 (3)+ 2.3=4.25 an= .65 (4)+ 2.3=4.9 an= .65 (5)+ 2.3=5.55

the problem states that n= 1, 2, 3, 4, 5 so you substitute that in each other the equations then add the sums together and multiply by 1/5

21.55(1/5) =4.31

This is reasonable in terms of the actual sum.

Pg.986 #62 & 70
62.)
a. t(n) = [17.6 + (0.83)(n - 1)]%

b. 2018 - 1967 = 51 so when the year is 2018, n = 51 and t(n) = [17.6 + (0.83)(51 - 1)]%
= [17.6 + (0.83)(50)]%
= (17.6 + 41.5)%
= 59.1%
70.)
30 + 32 + 34 + ... + (30 + 2*25)
30 + 32 + 34 + ... + 80
26/2 * (30 + 80) = 1,430

Pg. 1000 #70
A.)
22.49 / 22.12 = -1.02

22.86 / 22.49 = -1.02

23.41 / 22.86 = -1.02
B.)
the general term is of the form a_n = 22.12 * (1.02)^(n-1) for n = 1, 2, 3, ... (n = 1 represents 2003.)

C.) n = 8 to get a_8 = 22.12 * (1.02)^7 = -25.41 million people.