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If the average (arithmetic mean) of x and y is 40, and z – x = 60, wha
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12 Aug 2021, 07:23
12 Aug 2021, 07:23
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If the average (arithmetic mean) of x and y is 40, and z – x = 60, what is the average of y and z?
A. 20
B. 50
C. 65
D. 70
E. 140
A. 20
B. 50
C. 65
D. 70
E. 140
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Posts: 6218
Given Kudos: 136
If the average (arithmetic mean) of x and y is 40, and z – x = 60, wha
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12 Aug 2021, 07:28
12 Aug 2021, 07:28
1
Carcass wrote:
If the average (arithmetic mean) of x and y is 40, and z – x = 60, what is the average of y and z?
A. 20
B. 50
C. 65
D. 70
E. 140
A. 20
B. 50
C. 65
D. 70
E. 140
One approach is the assign values to x, y and z that satisfy the given conditions.
The average (arithmetic mean) of x and y is 40
Okay, two "nice" values are: x = 40 and y = 40
z – x = 60
Since we've let x = 40, then it must be the case that z = 100
What is the average of y and z?
If y = 40 and z = 100, then the average of y and z = (40+100)/2 = 70
Answer: D
NOTE: there was nothing special about the values I chose for x, y and z, other than the fact that they satisfied the given conditions. ANY other set of numbers will also yield the same answer.
For example, we could have used x = 20, y = 60 and z = 80, and this would have led to the same answer.
Try your own values to confirm this.
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Given Kudos: 9
Location: India
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WE:Engineering (Computer Software)
Re: If the average (arithmetic mean) of x and y is 40, and z x = 60, wha
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01 Aug 2022, 01:27
01 Aug 2022, 01:27
Theory
The average (arithmetic mean) of x and y is 40
Average of x and y = \(\frac{x + y}{2}\) = 40 (given)
=> x + y = 40*2 = 80 ...(1)
z – x = 60 (given) ...(2)
Adding (1) and (2) we get
x+ y + z - x = 80 + 60 = 140
=> y + z = 140
The average of y and z
Average of y and z = \(\frac{y + z}{2}\) = \(\frac{140}{2}\) = 70
So, Answer will be D.
Hope it helps!
Watch the following video to Learn the Basics of Statistics
- ➡ Average = Sum of all the Values / Total Number of Values
➡ Sum of All the values = Average * Total Number of Values
The average (arithmetic mean) of x and y is 40
Average of x and y = \(\frac{x + y}{2}\) = 40 (given)
=> x + y = 40*2 = 80 ...(1)
z – x = 60 (given) ...(2)
Adding (1) and (2) we get
x+ y + z - x = 80 + 60 = 140
=> y + z = 140
The average of y and z
Average of y and z = \(\frac{y + z}{2}\) = \(\frac{140}{2}\) = 70
So, Answer will be D.
Hope it helps!
Watch the following video to Learn the Basics of Statistics
