If C stands for cups, solve for C
48 - 2c = 0
l
subtract 48 from each side.
l
2c=-48
l
divide 48 by 2 ---> 24.
Answer:
The sample size is 
Step-by-step explanation:
From the question we are told that
The sample proportion is 
The margin of error is 
Given that the confidence level is 95% the level of significance is mathematically represented as



Next we obtain the critical value of
from the normal distribution table , the values is

The reason we are obtaining critical value of
instead of
is because
represents the area under the normal curve where the confidence level interval (
) did not cover which include both the left and right tail while
is just the area of one tail which what we required to calculate the margin of error
Generally the margin of error is mathematically represented as

substituting values




=> 
Answers:
- <u>24000 dollars</u> invested at 4%
- <u>18000 dollars</u> was invested at 7%
======================================================
Work Shown:
x = amount invested at 4%
If she invests x dollars at 4%, then the rest (42000-x) must be invested at the other rate of 7%
She earns 0.04x dollars from that first account and 0.07(42000-x) dollars from the second account
This means we have
0.04x+0.07(42000-x)
0.04x+0.07*42000-0.07x
0.04x+2940-0.07x
-0.03x+2940
This represents the total amount of money earned after 1 year.
We're told the amount earned in interest is $2220, so we can say,
-0.03x+2940 = 2220
-0.03x = 2220-2940
-0.03x = -720
x = -720/(-0.03)
x = 24000 dollars is the amount invested at 4%
42000-x = 42000-24000 = 18000 dollars was invested at 7%
----------------------
As a check, we can see that
18000+24000 = 42000
and also
0.04x = 0.04*24000 = 960 earned from the first account
0.07*18000 = 1260 earned from the second account
1260+960 = 2220 is the total interest earned from both accounts combined
This confirms our answers.