Answer: $35
Step-by-step explanation:
From the question, we are informed that the current bill of the person is $140.00 per month and that the person wants to decrease the bill by 25%.
To know the amount that the person needs to deduct, we have to calculate 25% of $140.00. This will be:
= 25% of $140
= 25/100 × $140
= 1/4 × $140
= 0.25 × $140
= $35
The person will need to remove $35. The person will now pay ($140 - $35) = $105 monthly.
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Answer:
a) The formula is given by mean 
the margin of error. Where the margin of error is the product between the critical value from the normal standard distribution at the confidence level selected and the standard deviation for the sample mean.
b) 
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
If the distribution for X is normal or if the sample size is large enough we know that the distribution for the sample mean 
is given by:
Part a
The formula is given by mean the margin of error. Where the margin of error is the product between the critical value from the normal standard distribution at the confidence level selected and the standard deviation for the sample mean.
Part b
The confidence interval for the mean is given by the following formula:
A) just change the numerator to anything more than 1
B) y=1/4+1
-2x + 5y = 8
2x + 2y = 6
----------------add
7y = 14
y = 14/7
y = 2
2x + 2y = 6
2x + 2(2) = 6
2x + 4 = 6
2x = 6 - 4
2x = 2
x = 2/2
x = 1
solution is (1,2)
