Given the total number of students are 180, the mean of data is 88g, and standard deviation is 1g.
A normal curve is a bell-shaped curve with symmetry about the mean and it spreads uniformly on both sides (left side and right side) of the mean.
The empirical rule is also called "68-95-99.7" rule. It says that :-
A) 68% of the data values fall between 1 standard deviation about mean (34% on left side and 34% on right side),
B) 95% of the data values fall between 2 standard deviations about mean (47.5% on left side and 47.5% on right side), and
C) 99.7% of the data values fall between 3 standard deviations about mean (49.85% on left side and 49.85% on right side).
According to distribution of normal curve and "68-95-99.7" empirical rule, we can say 49.85% of data values are above the mean within 3 standard deviations.
So it means 49.85% of total students report readings more than 88g.
Number of students reporting readings more than 88g = 49.85% of 180 = 0.4985 × 180 = 89.73
Hence, approximately 89 students report readings more than mean value.
A variable can be used to represent an unknown amount. Then you write an equation using the variable and based on the information you are given, and you solve the equation to find the unknown amount.
Here is an example.
Mary has money in a bank account. She received $20 for her birthday. She deposited the $20 in her account. After the deposit, she was told the account had a balance of $85. How much money did she have in the account before depositing the $20?
We don't know the amount she had before depositing the $20, so we will call that amount x. x is a letter used as a variable to represent an unknown amount.
She had x dollars in her account before depositing the $20.
After she deposited the $20, she now has x plus 20, or x + 20.
We are told her account now has $85, so x + 20 must equal 85.
That allows us to write an equation which we can then solve to find the amount of money she had in the account before depositing the $20.
x + 20 = 85
Subtract 20 from both sides.
x + 20 - 20 = 85 - 20
x + 0 = 65
x = 65
Since the variable x represents the amount of money in the account before depositing the $20 birthday money, we can now answer the question.
Mary had $65.
Answer:
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Step-by-step explanation:
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