CAT 2008: Quantitative Questions a Day 1 to 50 - The discussions

[rajeev_hts]

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Quantitative Question # 052
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Nbangalorekar bought a 10 kg of water-melon in Bangalore that had 99% water. After the water-melon was left outdoors for a day, it was 95% water. What was the weight of the dehydrated water-melon?


(1) 9.6 kg (2) 9.5 kg (3) 2 kg (4) can not be determined (5) none of these



Total solid= 1%of 10kg=0.1 Kg
let x Kg is water left after dehydration
then (x+0.1)*0.95=x
x=1.9
total wt = 1.9+0.1=2Kg

Op(3)

[sameerkalra86]

2)
Hey atom, if we jst try to expand it ....

(1*2*3)*(1*2*3*4*5)*(1*2*3*4*5*6*7)

We can see that first two products (3!*5!) comes out to be 8*9*10

So...

= (8*9*10)*(1*2*3*4*5*6*7) = 10!

[asifn]

hi Rajeev..well brother gr8 work but i m still unable to understand about the logic ..i mean how to approach ..could u plz explain it in a more better way..i guess except u none has solved this ...cheers

[avenger007]

hei...I can't understand the concept of no: of steps taken in an escalator..plz help me wid dis,
(speed of a person/speed of escalator) = (no: of steps on moving escalator / no: of steps of the person when escalator is off)

cld any one plz explain the concept..?

[lsrgandhi]

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Quantitative Question # 088
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If f(x) = x^2 - 2x then for how many distinct real α is f(f(f(f(α)))) = 3?


(1) 3 (2) 6 (3) 5 (4) 9 (5) none of these

Answer for this is (4) 9

Solution:
From the outermost 'f' we find the distinct values of 'x' for which f(x)=3. For this we have x=3 or -1.

Now for second 'f' we find out distinct 'x' such that f(x)=3 and f(x)=-1.

Continuing in this way, we get the following 9 distinct and real values of 'x' satisfying f(f(f(f(x)))) = 3:
3, -1, 1,
1+2^(1/2),
1-2^(1/2),
1+(2+2^(1/2))^(1/2),
1-(2+2^(1/2))^(1/2),
1+(2-2^(1/2))^(1/2),
1-(2-2^(1/2))^(1/2).