Answer:
<em>Cathy was born in 1980 and she was 18 years old in 1998</em>
Step-by-step explanation:
<u>Equations</u>
This is a special type of equations where all the unknowns must be integers and limited to a range [0,9] because they are the digits of a number.
Let's say Cathy was born in the year x formed by the ordered digits abcd. A number expressed by its digits can be calculated as
In 1998, Cathy's age was
And it must be equal to the sum of the four digits
Rearranging
We are sure a=1, b=9 because Cathy's age is limited to having been born in the same century and millennium. Thus
Operating
If now we try some values for c we notice there is only one possible valid combination, since c and d must be integers in the range [0,9]
c=8, d=0
Thus, Cathy was born in 1980 and she was 18 years old in 1998. Note that 1+9+8+0=18
X is the number of movies for the cost of the plan to be the same.
4.25x=36+3.5x
4.25x-3.5=36
0.75x=36
x=36/0.75
x=48
Answer:
-2
Step-by-step explanation:
f(x) = -x + 2
f(4) = -(4) + 2
f(4) = -2
Answer:
We have to reject the null hypothesis because the t-value is greater than the critical value .
Step-by-step explanation:
Answer:
7800
Step-by-step explanation: