Julian had five indoor potted plants, each of which - in order to

Question

Julian had five indoor potted plants, each of which - in order to survive - only needed to be watered once in a certain number of days. That number was not the same for all five plants. Julian last watered the plants - all of them - at noon on a Monday. He left home that Thursday and returned the following Thursday at noon. None of the plants were watered while Julian was away, and none of them died from any cause except lack of watering. At least one plant was alive when Julian returned. How many were alive in all?

(1) Exactly two plants were such that they would have survived only if Julian had watered them on the day he left home.
(2) Three plants were identical in terms of watering needs.

(1) Exactly two plants were such that they would have survived only if Julian had watered them on the day he left home.
(2) Three plants were identical in terms of watering needs.

Bunuel · Accepted Answer

Julian had five indoor potted plants, each of which - in order to survive - only needed to be watered once in a certain number of days. That number was not the same for all five plants. Julian last watered the plants - all of them - at noon on a Monday. He left home that Thursday and returned the following Thursday at noon. None of the plants were watered while Julian was away, and none of them died from any cause except lack of watering. At least one plant was alive when Julian returned. How many were alive in all?

(1) Exactly two plants were such that they would have survived only if Julian had watered them on the day he left home.
(2) Three plants were identical in terms of watering needs.

We know that Julian watered the plants at noon on Monday and then left on Thursday for one week. We are also told that  at least one plant survived his absence . Our task is to determine exactly how many plants survived.

(1) Exactly two plants were such that they would have survived only if Julian had watered them on the day he left home.

The statement tells us that two plants would have survived only if they were watered on Thursday. This implies that these two plants did not survive Julian's absence, as they were not watered on the day he left. However, there could be other plants, say one additional plant, that also couldn't have survived the absence because it required watering even more frequently than these two. It's also possible that only these two plants did not survive and the other three did. Not sufficient.

(2) Three plants were identical in terms of watering needs.

If the three identical plants include the one that survived, then at least three plants would have survived. However, we do not know how many plants actually survived, as it’s possible that two other plants needed even less frequent watering and could have survived as well. Not sufficient.

(1)+(2) The three plants with identical watering needs from (2) could not include the two plants that died from (1), because we are told exactly two plants had that specific need. Therefore, the three identical plants must include the one that survived, and thus all three of these plants survived. Sufficient.

Answer: C.

HarshitaV · Answer

Thanks Bunuel! Happy to see I was thinking on the right lines.

Harsh_ · Answer

Given:  
5 Plants
Last Watered 12:00 PM Monday
Left Home - Thursday
Returned Home - Next Thursday
None Watered during this time
-> 1 or More Alive 
 To Find : How many are Alive

I. 2 would have survived => 2 have died 
 Remaining = 3 , Out of this given -> 1 survived, we don't know anything about other 2 Plants. - Not Sufficient

II. 3 have Identical iin terms of water needs
 we don't know anything about survival - Not Sufficient

I+II
 
2 Died
1 Alive
3 Identical in terms of Needs => They are Alive or else it would have been the case 3 died which is not true

Answer. C

Usernamevisible · Answer

Great solution from Bunuel, I am just highlighting some of the important things in his solution

Julian had five indoor potted plants, each of which - in order to survive - only needed to be watered once in a certain number of days. That number was not the same for all five plants. Julian last watered the plants - all of them - at noon on a Monday. He left home that Thursday and returned the following Thursday at noon. None of the plants were watered while Julian was away, and none of them died from any cause except lack of watering. At least one plant was alive when Julian returned. How many were alive in all?

(1) Exactly two plants were such that they would have survived only if Julian had watered them on the day he left home.
(2) Three plants were identical in terms of watering needs.

We know that Julian watered the plants at noon on Monday and then left on Thursday for one week. We are also told that    at least one plant survived his absence   . Our task is to determine exactly how many plants survived.

(1) Exactly two plants were such that they would have survived only if Julian had watered them on the day he left home.

The statement tells us that two plants would have survived only if they were watered on Thursday. This implies that these two plants did not survive Julian's absence, as they  were not watered on the day he left   (I have additionally highlighted in the passage where it says "LAST WATERED")   . However, there could be other plants, say one additional plant, that also couldn't have survived the absence because it required watering even more frequently than these two. It's also possible that only these two plants did not survive and the other three did. Not sufficient.

(2) Three plants were identical in terms of watering needs.

If the three identical plants include the one that survived, then at least three plants would have survived. However, we do not know how many plants actually survived, as it’s possible that two other plants needed even less frequent watering and could have survived as well. Not sufficient.

(1)+(2) The three plants with identical watering needs from (2) could not include the two plants that died from (1), because we are told exactly two plants had that specific need. Therefore, the three identical plants must include the one that survived, and thus all three of these plants survived. Sufficient.

Answer: C.

Additional - because statement (1) specifies  exactly two plants with that particular watering requirement , the group of three identical plants in statement (2) cannot share that same requirement. if statement (1) had merely said that two plants died, without specifying that they had that specific watering need, then it would be possible for the two dead plants to belong to a larger group of three identical plants, creating multiple survival scenarios.

basicboehly · Answer

Struggling to differentiate between "That number was not the same for all five plants" and "Three plants were identical in terms of watering needs". Aren't they contradicting each other?

Bunuel · Answer

They are not contradictory.

“That number was not the same for all five plants” means only that the five plants did not all have the same watering requirement. It does not mean that every plant had a different requirement.

So three plants could have identical watering needs, while the other two had different needs.

egmat · Answer

Hi basicboehly,

Good catch, this is a wording trap, and once you see it the "contradiction" disappears.

Look closely at what the stem actually says:  "That number was not the same for all five plants."  This only rules out  one  situation - that all five share the exact same interval. It does  not  say all five are different from each other.

So "not the same for all five" just means:  they are not all identical.  As long as at least  two  intervals differ, the condition is satisfied.

Now put Statement ( 2 ) next to it - three plants identical:

- Three plants share interval  A 
- The other two have intervals that are  not both A  (say  B  and  C , or B and B as long as B ≠ A)

That lineup has three matching plants  and  still isn't "all five the same," because plants  4  and  5  break the tie. No contradiction - both conditions hold at the same time.

The only thing the stem forbids is all  five  being equal. Any grouping short of that is fair game, including a group of  three .

A quick everyday version to lock it in:  "The five students are  not all  the same height." Does that clash with "three of them are the same height"? Not at all - three can match while the other two differ, and the group still isn't uniformly one height.

So treat "not the same for  all " as  not every single one is equal  - never as  every one is distinct . That single reading is what makes Statements ( 1 ) and ( 2 ) combine cleanly into three survivors, giving you  C .

Answer: C

Julian had five indoor potted plants, each of which - in order to

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