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manager.png
The figure above illustrates a managerial table of organization in which each person, except those on the lowest level, supervises exactly two persons on the next lower level. If each lower level contains exactly one person more than the next higher level, which of the following could be the total number of persons in an organization built on such a pattern?

(A) 7
(B) 16
(C) 20
(D) 28
(E) 35

1 + 2 + 3 + 4 + 5 + 6 + 7 = 28.

Answer: D.

@bunuel - Can you please explain the above logic?

Thanks.
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Asifpirlo
Attachment:
manager.png
The figure above illustrates a managerial table of organization in which each person, except those on the lowest level, supervises exactly two persons on the next lower level. If each lower level contains exactly one person more than the next higher level, which of the following could be the total number of persons in an organization built on such a pattern?

(A) 7
(B) 16
(C) 20
(D) 28
(E) 35

An organization built on such a pattern is shown in the diagram. Every little circle is a person. If it has only two levels, number of people in it will be 1+2.
If it has 3 levels, number of people in it will be 1+2+3. If it has 4 levels, number of people in it will be 1+2+3+4.

In the diagram, they show 5 levels so it has 1+2+3+4+5 people in it and so on...

Now either add a few more numbers:
1+2+3+4+5 = 15
15+6 = 21
21 + 7 = 28
(You got one of the numbers on the list). 28 is your answer.

Or look for the option which can be written as n(n+1)/2.
28 = 7*4.
When we multiply it by 2, we get 7*8 which is n(n+1).

Answer (D)
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Asifpirlo
Attachment:
manager.png
The figure above illustrates a managerial table of organization in which each person, except those on the lowest level, supervises exactly two persons on the next lower level. If each lower level contains exactly one person more than the next higher level, which of the following could be the total number of persons in an organization built on such a pattern?

(A) 7
(B) 16
(C) 20
(D) 28
(E) 35

An organization built on such a pattern is shown in the diagram. Every little circle is a person. If it has only two levels, number of people in it will be 1+2.
If it has 3 levels, number of people in it will be 1+2+3. If it has 4 levels, number of people in it will be 1+2+3+4.

In the diagram, they show 5 levels so it has 1+2+3+4+5 people in it and so on...

Now either add a few more numbers:
1+2+3+4+5 = 15
15+6 = 21
21 + 7 = 28
(You got one of the numbers on the list). 28 is your answer.

Or look for the option which can be written as n(n+1)/2.
28 = 7*4.
When we multiply it by 2, we get 7*8 which is n(n+1).

Answer (D)


Thanks Karishma for the explanation. Actually I was misled by the question stem. I was trying to add one more person in each lower level (excluding the top most level person) and thus got confused.
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Asifpirlo
Attachment:
manager.png
The figure above illustrates a managerial table of organization in which each person, except those on the lowest level, supervises exactly two persons on the next lower level. If each lower level contains exactly one person more than the next higher level, which of the following could be the total number of persons in an organization built on such a pattern?

(A) 7
(B) 16
(C) 20
(D) 28
(E) 35

An organization built on such a pattern is shown in the diagram. Every little circle is a person. If it has only two levels, number of people in it will be 1+2.
If it has 3 levels, number of people in it will be 1+2+3. If it has 4 levels, number of people in it will be 1+2+3+4.

In the diagram, they show 5 levels so it has 1+2+3+4+5 people in it and so on...

Now either add a few more numbers:
1+2+3+4+5 = 15
15+6 = 21
21 + 7 = 28
(You got one of the numbers on the list). 28 is your answer.

Or look for the option which can be written as n(n+1)/2.
28 = 7*4.
When we multiply it by 2, we get 7*8 which is n(n+1).

Answer (D)


Hi Karishma,

I am confused. If we have two persons in the second level and three in the next level, then one person will be left in the 3rd level. As question says each person from the higher level supervises exactly two persons of the next lower level. Can we count the single person from the third level.
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Attachment:
manager.png
The figure above illustrates a managerial table of organization in which each person, except those on the lowest level, supervises exactly two persons on the next lower level. If each lower level contains exactly one person more than the next higher level, which of the following could be the total number of persons in an organization built on such a pattern?

(A) 7
(B) 16
(C) 20
(D) 28
(E) 35

An organization built on such a pattern is shown in the diagram. Every little circle is a person. If it has only two levels, number of people in it will be 1+2.
If it has 3 levels, number of people in it will be 1+2+3. If it has 4 levels, number of people in it will be 1+2+3+4.

In the diagram, they show 5 levels so it has 1+2+3+4+5 people in it and so on...

Now either add a few more numbers:
1+2+3+4+5 = 15
15+6 = 21
21 + 7 = 28
(You got one of the numbers on the list). 28 is your answer.

Or look for the option which can be written as n(n+1)/2.
28 = 7*4.
When we multiply it by 2, we get 7*8 which is n(n+1).

Answer (D)


Hi Karishma,

I am confused. If we have two persons in the second level and three in the next level, then one person will be left in the 3rd level. As question says each person from the higher level supervises exactly two persons of the next lower level. Can we count the single person from the third level.

Hi Akshdeep,

Since every lower level has only 1 person more than the next higher level therefore if the second level has two individual then the third level must have 3 individuals

however you need to understand that one individual can be and will be supervised by more than one supervisors in that case

so the three individuals will be supervised by two supervisors and one of the three individuals on level three will be supervised by both supervisors at just higher level. and this process will continue for the next lower levels as well.

I hope it answers your question!!!
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akshdeep28
Attachment:
manager.png
The figure above illustrates a managerial table of organization in which each person, except those on the lowest level, supervises exactly two persons on the next lower level. If each lower level contains exactly one person more than the next higher level, which of the following could be the total number of persons in an organization built on such a pattern?

(A) 7
(B) 16
(C) 20
(D) 28
(E) 35

An organization built on such a pattern is shown in the diagram. Every little circle is a person. If it has only two levels, number of people in it will be 1+2.
If it has 3 levels, number of people in it will be 1+2+3. If it has 4 levels, number of people in it will be 1+2+3+4.

In the diagram, they show 5 levels so it has 1+2+3+4+5 people in it and so on...

Now either add a few more numbers:
1+2+3+4+5 = 15
15+6 = 21
21 + 7 = 28
(You got one of the numbers on the list). 28 is your answer.

Or look for the option which can be written as n(n+1)/2.
28 = 7*4.
When we multiply it by 2, we get 7*8 which is n(n+1).

Answer (D)


Hi Karishma,

I am confused. If we have two persons in the second level and three in the next level, then one person will be left in the 3rd level. As question says each person from the higher level supervises exactly two persons of the next lower level. Can we count the single person from the third level.

Hi Akshdeep,

Since every lower level has only 1 person more than the next higher level therefore if the second level has two individual then the third level must have 3 individuals

however you need to understand that one individual can be and will be supervised by more than one supervisors in that case

so the three individuals will be supervised by two supervisors and one of the three individuals on level three will be supervised by both supervisors at just higher level. and this process will continue for the next lower levels as well.

I hope it answers your question!!!

Yes, I got it perfectly...Thanks for the instant reply to my query...I was really confused as I was not counting the single person left in each row. Thanks.
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2 approaches:

1. Just add the numbers and match the options. According to the question, the structure has 1,2,3,4,5 - these are not in option. Add 6 and you get 15, which is not in option. Add 6 and 7 and you get 28.

2. it is an AP problem. Common difference is 1. Although, not needed in this case as the numbers are small enough for calculations
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