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Re: URGENT help required, OG 13 questions [#permalink]
08 Apr 2013, 10:41

rajrj17 wrote:

Q2) the price of lunch for 15 people was $207.00, including a 15% gratuity for service. What was the average price per person EXCLUDING the gratuity? a)11.73 b)12 c)13.8 d)14 e)15.87

Here the word EXCLUDING is used. So 0.15 * 207=$31.05 Therefore,207-31.05=$175.95

So the average cost per person=175.75/15=11.73 So ans should be (A) IMO.

the stem before the question states that 207 INCLUDES 15% gratuity. hence 1.15x = 207 and bill (without gratuity) would have only been 180. add 15% gratuity and that arrives at the total bill for 207. now the question asked is to calculate amount per person EXCLUDING gratuity which is per person share of $180 bill that will be $12 when shared equally between 15 people)

Re: URGENT help required, OG 13 questions [#permalink]
08 Apr 2013, 10:42

you guys are amazing! thank you so much! I've actually recently finished the whole of OG13 PS, so I just posted my questions. Q1) D Q2) B Q3) B Q4) D Q5) D Q6)E Q7) D Q8)D Q9) B

Re: URGENT help required, OG 13 questions [#permalink]
08 Apr 2013, 22:26

1

This post received KUDOS

[quote="Zarrolou"]That's a lot of questions !

Q1)A ladder of a fire truck is elevated to an angle of 60 degrees and extended to a length of 70 feet. if the base of the ladder is 7 fet above the ground, how many feet above the ground does the ladder reach?

The ladder forms a 30 60 90, triangle which has dimentions 1x \sqrt{3} 2, the hip is 70=2x so x=35, the H of the triangle is 35\sqrt{3}, but the ladder is 7 feet from the ground => it reaches [m]7+35[squar

I dont understand how youve put hyp=2x. Hyp is opp the 90 deg angle, so shouldnt ishould we put it equal to under root three? I dont understand OGs explanation

Re: URGENT help required, OG 13 questions [#permalink]
08 Apr 2013, 22:37

Zarrolou wrote:

Q3) for any psitive integer n, the sum fo the first n positive integers equals [n(n+1)]/2. what si the sum of all the even integers betwen 99 and 301?

100 ... 200 ... 300 Between 200 and 100 there are 200/2-100/2+1=51 even integers Between 300 and 200 there are 300/2-200/2+1=51 even integers But we counted 200 twice, so tot even entegers = 51+51-1=101. As you can see their mean is 200 So tot sum is200*101=20200 IMO B

Why are you adding one both times for even integers?

Re: URGENT help required, OG 13 questions [#permalink]
08 Apr 2013, 22:45

usre123 wrote:

Zarrolou wrote:

Q3) for any psitive integer n, the sum fo the first n positive integers equals [n(n+1)]/2. what si the sum of all the even integers betwen 99 and 301?

100 ... 200 ... 300 Between 200 and 100 there are 200/2-100/2+1=51 even integers Between 300 and 200 there are 300/2-200/2+1=51 even integers But we counted 200 twice, so tot even entegers = 51+51-1=101. As you can see their mean is 200 So tot sum is200*101=20200 IMO B

Why are you adding one both times for even integers?

It`s the formula. let me give you an example, between 4 and 8 there are 3 even numbers (4,6,8). If you don t add 1, you obtain 8/2=4 4/2=2 so 4-2=2 and not 3. That`s why you have to add one.
_________________

It is beyond a doubt that all our knowledge that begins with experience.

Re: URGENT help required, OG 13 questions [#permalink]
08 Apr 2013, 22:50

usre123 wrote:

Zarrolou wrote:

That's a lot of questions !

Q1)A ladder of a fire truck is elevated to an angle of 60 degrees and extended to a length of 70 feet. if the base of the ladder is 7 fet above the ground, how many feet above the ground does the ladder reach?

I dont understand how youve put hyp=2x. Hyp is opp the 90 deg angle, so shouldnt ishould we put it equal to under root three? I dont understand OGs explanation

The proportions in a 30 60 90 are 1x:x\sqrt{3}:2x. The text says that "it extends for 70 feet", and this side is opposite to the right angle and therefore the longest one and therefore ( because 2>\sqrt{3}) equals 2x. Now that you have x, you can obtain all the sides. Hope it s clear now
_________________

It is beyond a doubt that all our knowledge that begins with experience.

Re: URGENT help required, OG 13 questions [#permalink]
09 Apr 2013, 02:28

Expert's post

usre123 wrote:

Q1)A ladder of a fire truck is elevated to an angle of 60 degrees and extended to a length of 70 feet. if the base of the ladder is 7 fet above the ground, how many feet above the ground does the ladder reach? a) 35 b) 42 c) 35 \sqrt{3} d) 7+ 35\sqrt{3} e) 7+42\sqrt{3} ...