DS questions (OG 12).

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gdk800: Senior | Next Rank: 100 Posts; Posts: 54; Joined: Tue Feb 02, 2010 5:17 am; Thanked: 2 times

DS questions (OG 12).

by gdk800 » Fri Nov 26, 2010 12:57 am

Q1. What is the median number of employees assigned per project for the projects at Company Z ?
(1) 25 percent of the projects at Company Z have 4 or more employees assigned to each project.
(2) 35 percent of the projects at Company Z have 2 or fewer employees assigned to each project.

OA is C

Q2. If n is a positive integer, what is the tens digit of n?
(1) The hundreds digit of 10n is 6.
(2) The tens digit of n + 1 is 7.

OA is A

Can some one explain the first option of second question saying the hundreds digit of 10n is 6

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Source: Beat The GMAT — Data Sufficiency | Fri Nov 26, 2010 12:57 am

junegmat221: Junior | Next Rank: 30 Posts; Posts: 24; Joined: Wed Apr 28, 2010 4:03 am

by junegmat221 » Fri Nov 26, 2010 1:25 am

For example.
HTU(H-Hundred's digit, T-Ten's digit, U-Unit Digit)
Number can be 10n = 620 (H-6,T-2,U-0)
But ensure that n is a positive integer when divided by ten(because it is stated explicitly)
other examples 1620, 22620 Just keep the third digit from the right as 6
Ensure u select the 10n as a multiple of 10..

Now u need the tens digit of n.
Divide the same number by ten.

TU(T-Ten's digit, U-Unit's Digit)
In this case 620/10 = n = 62 (T-6,U-2)
Now u need the Tens digit of (N).
Which is '6'.

Hope it clarifies.

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selango: Legendary Member; Posts: 1460; Joined: Tue Dec 29, 2009 1:28 am; Thanked: 135 times; Followed by:7 members

by selango » Fri Nov 26, 2010 5:31 am

stmt1,

The hundreds digit of 10n is 6.

n can be any integer from 60 to 69.Tens digit is 6.

Suff

stmt2,

The tens digit of n + 1 is 7

If the unit's digit is 9,ten's digit is 6

If the unit's digit is 0,ten's digit is 7

Insuff

Pick A

--Anand--

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rishab1988: Master | Next Rank: 500 Posts; Posts: 332; Joined: Tue Feb 09, 2010 3:50 pm; Thanked: 41 times; Followed by:7 members; GMAT Score:720

by rishab1988 » Fri Nov 26, 2010 6:54 am

For Q1 the answer is C.

The question talks about median so were are concerned about the (50th +51 th)/2 .Lets assume no of projects =100

1) clearly insufficient.Since this statement talks about any no of employees from 4 to literally infinity.We can say that the last 25 projects have 4 or more employees.But we have no info about the rest of the projects.All the projects from 1 to 74 could have only 1 employee.In that case median=1.If all the projects from 1 to 74 have 2 employees,then median =2.Two values hence insufficient.

2) Same reason 2 insufficient.We know that the first 35 percentile of projects have 2 or fewer employees but we cannot say anything about the 50th percentile project.

Combining 1 and 2.

We know from 2 that first 35 projects have 2 or fewer employees.Since we know that the no of people with 4 or more employees is 25%.We can infer that 40% of projects have 3 employees.The median is 3

Q2.

let n = ab

Then the question is what is a?

1) 10*n = ab0.When you multiply any no by 10 the units digit becomes zero].The statement says that the hundreds digit of ab0 is 6 or in other words a=6.Sufficient

2) lets assume ab=69 then ab+1=70.so tens digit or a =6

But if ab=72 then ab+1=73.so the tens digit is 7.

2 values hence insufficient.

Answer A

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rishab1988: Master | Next Rank: 500 Posts; Posts: 332; Joined: Tue Feb 09, 2010 3:50 pm; Thanked: 41 times; Followed by:7 members; GMAT Score:720