a)
Let t represents number of years after 1900
so that means for 1900, value of t is 0
We are given point as (0,55)
and it says that life expectancy increases by 0.2
so that means slope,m=0.2
equation of line is y=mt +b
or y=0.2t +b
now we use point (0,55)
55 =0.2(0) +b
55 =0+b
55= b
so b=55
plug it back into the equation,we get
y=0.2t +55
b)
We are given y=73
so we plug it into the equation we got in part a and solve for t
y=0.2t +55
73 =0.2t +55
73-55 =0.2t
18 =0.2t
18/0.2 =t
90 =t
so t=90
This means the birth year =1900+t =1900+90 =1990
Let m the tens digit and n the ones
the Original number is 10m+n
7(m+n) =10m+n
7m+7n=10m+n
6n=3m
Reversing the number 10n+m
10n+m=18+n+m
9n=18
n=2
6n=3m
6(2)=3m
3m=12
m=4
the number is 10m+n=10(4)+2=42
Answer:
61
Step-by-step explanation:
a = 17
d = 21 - 17 = 4
12th day: 17 + 4(12 - 1)
17 + 44
61
