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In Goshawk-Eurasian nature reserve 30 percent of the birds [#permalink]
27 Apr 2013, 02:45

Expert's post

00:00

A

B

C

D

E

Difficulty:

25% (medium)

Question Stats:

78% (02:26) correct
22% (02:03) wrong based on 91 sessions

In Goshawk-Eurasian nature reserve 30 percent of the birds are Hawks, and 40 percent of the non-Hawks are Paddyfield-Warblers. If there are 25 percent as many Kingfishers as Paddyfield-Warblers in the reserve, then what percent of the birds in the nature reserve are not Hawks, Paddyfield-Warblers, or Kingfishers?

A. 25% B. 35% C. 45% D. 70% E. 80%

P.S: Bunuel/Karishma-Can you please come up with a detail explanation for the solution. And is it a 700+ problem? I doubt although...

Re: In Goshawk-Eurasian nature reserve 30 percent of the birds [#permalink]
27 Apr 2013, 03:12

1

This post received KUDOS

I'm not Bunuel/Karishma, but I can try to help you. I don't think that it is 700+ problem. You even don't need any equations. Just be accurate with percents.

Since the problem doesn't depend on the number of birds in reserve you can suppose that there are 100 birds. From them 100*0.3=30 are Hawks.So, there are 70 non-Hawks.

There are 0.4*70=28 Paddyfield-Warblers. Therefore, there are 0.25*28=7 Kingfishers.

The total number of birds in the nature reserve that are not Hawks, Paddyfield-Warblers, or Kingfishers is 100-30-28-7=35.

The answer is B.

Hope this helps. _________________

I'm happy, if I make math for you slightly clearer And yes, I like kudos:)

Re: In Goshawk-Eurasian nature reserve 30 percent of the birds [#permalink]
27 Apr 2013, 10:15

Expert's post

smyarga wrote:

I'm not Bunuel/Karishma, but I can try to help you. I don't think that it is 700+ problem. You even don't need any equations. Just be accurate with percents.

Since the problem doesn't depend on the number of birds in reserve you can suppose that there are 100 birds. From them 100*0.3=30 are Hawks.So, there are 70 non-Hawks.

There are 0.4*70=28 Paddyfield-Warblers. Therefore, there are 0.25*28=7 Kingfishers.

The total number of birds in the nature reserve that are not Hawks, Paddyfield-Warblers, or Kingfishers is 100-30-28-7=35.

The answer is B.

Hope this helps.

Thanks smyarga- I was somewhat confused with my own explanation...! It's clear now.. _________________

Re: In Goshawk-Eurasian nature reserve 30 percent of the birds [#permalink]
09 Sep 2013, 22:14

In Goshawk-Eurasian nature reserve 30 percent of the birds are Hawks, and 40 percent of the non-Hawks are Paddyfield-Warblers. If there are 25 percent as many Kingfishers as Paddyfield-Warblers in the reserve, then what percent of the birds in the nature reserve are not Hawks, Paddyfield-Warblers, or Kingfishers?

A. 25% B. 35% C. 45% D. 70% E. 80%.

This question can be solved using at least 2 methods. Lets look at them. 1. We are given the following percentages: 30 (70), 40 (60), 25 (75). There are two threads from here. First starts at 30% and finishes there. Second one starts at 70, then 40, and then 25. We need a value that is divisible by 7, 2, and 5 at least once. lets pick a number now, say 700. So say if Non Hawks are 700 (this is 70% of the total, so total = 1000), then Paddy Warbs are 2/5 x 700 = 1400/5 = 280. Kingfishers, therefore, are 280/4 = 70. Lets add them up. 300 hawks + 280 Peddy Warbs + 70 kingsifhers = 650. So all others are 1000 - 650= 350 or 35% of total birds. The main job here to to identify the smart number to start the question with. This can be time consuming, but once identified, this question can be solved fairly quickly.

2. Another method: If X is total --> Non Hawks = 0.7X --> Warbs = 0.4(0.7X) --> KFs = 0.25(0.4(0.7X)). Our job is to find out : (0.3X + 0.28X + 0.07X)/ X. OR 0.65X/X = 0.65. We need to find 1-0.65 = 0.35 or 35%.

Re: In Goshawk-Eurasian nature reserve 30 percent of the birds [#permalink]
26 Jul 2014, 21:11

Hi Smyarga,

Can you please explain what " If there are 25 percent as many Kingfishers as Paddyfield-Warblers" means? Though i got the ans right, didnt get the clarity of the above phrase. Thanks in advance.

Re: In Goshawk-Eurasian nature reserve 30 percent of the birds [#permalink]
27 Jul 2014, 16:51

Expert's post

sri30kanth wrote:

Hi Smyarga,

Can you please explain what " If there are 25 percent as many Kingfishers as Paddyfield-Warblers" means? Though i got the ans right, didnt get the clarity of the above phrase. Thanks in advance.

This simply means that the number of Kingfishers is 25% of the number of Paddyfield-Warblers. _________________