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How old is Brenda?

Puzzling Asked on June 28, 2021

Five friends (Adele, Brenda, Carol, Dana and Emily) were born peculiarly
in consecutive years.

It is known from their diaries that:

Carol was born 2 years before Dana and is not the oldest of them all.

Brenda is not younger than Emily.

Brenda is not the oldest of them all.

If Emily is 25 years old and everyone has already had their birthday
this year, how old is Brenda?

The alternatives given in my book are as follows:

  1. 28 years
  2. 27 years
  3. 26 years
  4. 29 years

How exactly should I get Brenda’s age? At this point I’m stuck because it doesn’t seem to be possible to determine who’s the oldest of the group.

So far I have:

Carol > someone > Dana

Then

Emily > Brenda

Then "Brenda is not the oldest of all" seems to overlap with Carol because both state that those two girls are not the oldest of all. So who’s the youngest? It only mentions Emily but it doesn’t indicate anything else. Can Brenda’s age be determined with these few clues?

For reference this problem was obtained from my Logic and reason book from 2000s, and it seems to be an adaptation from a reprinted copy of Martin Gardner’s 1970s Puzzle carnival.

Can a logic grid be used here? Please try to include a solution with step by step explanation so I can understand because I’m lost here. Justification is also important.

2 Answers

Answer

Reasoning

Answered by hexomino on June 28, 2021

@hexomino has already answered this question, but here's my answer, which is more visual, and should be easy to follow.

From the puzzle, we can determine that:

This means that

We also know that

We can arrange the sisters from right-to-left, with the eldest, on the right:

Since

Also,

And since

In both cases,

Answered by marsnebulasoup on June 28, 2021

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