GMAT Data Sufficiency Discussions

1.31

In this case, P can be equal to = 32,33,34,35,36
None of them is a prime number, so yes Positive integer P be expressed as the product of 2 integers, Each of which is greater than 1.

Statement I sufficient.
2. P is Odd
Well except 2, all prime numbers are odd, so P can be something like 5,7,17. In that case P cannot be expressed as the product of 2 integers

Statement II, insufficient.

Combining 2 statement
P can be equal to =33,35
In both case can be expressed as the product of 2 integers.
So Together also sufficient.



Why do we need to combine the two statements when 1 is sufficient and 2 is not? It will correspond to Option A. of the DS type questions on GMAT.
Yesterday Nan parked her car at a certain parking garage that charges more for the first hour than for each additional hour. If Nans total parking charge at the garage yesterday was $3.75, for how many hours of parking was she charged?

(1) Parking charges at the garage are $0.75 for the first hour and $0.50 for each additional hour
or fraction of an hour.
(2) If the charge for the first hour had been $1.00, Nans total parking charge would have been
$4.00.


d both r sufficient
Yesterday Nan parked her car at a certain parking garage that charges more for the first hour than for each additional hour. If Nans total parking charge at the garage yesterday was $3.75, for how many hours of parking was she charged?

(1) Parking charges at the garage are $0.75 for the first hour and $0.50 for each additional hour
or fraction of an hour.
(2) If the charge for the first hour had been $1.00, Nans total parking charge would have been
$4.00.


We cant answer even by combining both as we donot know whether its 7 hrs or 6 hr and some mins. . .
Yesterday Nan parked her car at a certain parking garage that charges more for the first hour than for each additional hour. If Nan's total parking charge at the garage yesterday was $3.75, for how many hours of parking was she charged?

(1) Parking charges at the garage are $0.75 for the first hour and $0.50 for each additional hour
or fraction of an hour.
(2) If the charge for the first hour had been $1.00, Nan's total parking charge would have been
$4.00.


My take:

Opt I. Charges for first hour = 0.75$
Total charge = 3.75$ ==> charge for remaining hours = $3.00
rate for each additional hour/fraction hour = $ 0.50
Question doesnt ask how many hours was she parked rather it asks how many hours of parking she was charged. So

1 hr + (3.00/0.5) = 7 hrs. Option I is sufficient.

Opt II. If parking charge for 1st hr = $ 1.00, remainder charge = 4.00 -1 = $ 3.00. However without the information of the parking charge rate it's not possible to calculate the number of hours of parking charge. Hence II is insufficient.
Ans: A.

My turn!

Q1)If t is NOT equal to zero, is r greater than zero?

(1)rt=12
(2)r+t=7

Q2)If m is a positive integer, then m*m*m(m-cubed) has how many digits?
(1)m has 3 digits
(2)m*m has 5 digits

Q1)If t is NOT equal to zero, is r greater than zero?

(1)rt=12
(2)r+t=7

Solution:

OPT I: t != 0 ==> t 0
rt = 12, possible values are {r,t}= {-12,-6,-2,-4,-3,-1,1,2,3,4,6,12} Hence NOT Sufficient.

OPTII: r+t = 7
r0 e.g. -1 + 8 = 7
r>0,tNot Sufficient.

OPT I and OPT II : only one pair out of {r,t}= {-12,-6,-2,-4,-3,-1,1,2,3,4,6,12} satisfies the equality{r,t}={3,4}: rt=12 , r+t=7. Hence it is determined that r> 0

Ans: C

Q2)If m is a positive integer, then m*m*m(m-cubed) has how many digits?
(1)m has 3 digits
(2)m*m has 5 digits

Solution:

OPT I: m has 3 dig ==> m = {100,999}
==> m(cube) = {1000000(7 digits), 997002999(9 digit) }
Hence m(cube) varies between 7 digits to 9 digits.
NOT Sufficient.

OPT II :m*m has 5 digits ==> m*m = {10000, 99999}
==> m = {100, 316}
==> m*m*m = {1000000(7 digits) , 31554496(8 digits)}
Hence m(cube) varies between 7 digits and 8 digits.
NOT Sufficient

OPT I and OPT II : m = {100, 316} is a subset of m = {100,900} . Hence both options are NOT Sufficient.
Ans: E.

Note: This problem does involve some approximations. WE dont need to actually calulate 999(cube), just an approximation of number of digits is sufficent.

1)circle C and Like K, lie in a plane XY, If C has center @ origin with radius 1, does like K intercects C

a The intercept of like K>1
b Slope of like K -1/10

2) K Not equal To 0,1 & -1 IS 1/K>0

a 1/k-1>1
b 1/k+1>0

Come __ON PG>>>>SSSS.....Guys One more please answer this

If set S consists of the numbers 1, 5, -2, 8, and n, is 0
(1) The median of the numbers in S is less than 5.
(2) The median of the numbers in S is greater than 1.
Come __ON PG>>>>SSSS.....Guys One more please answer this
If set S consists of the numbers 1, 5, -2, 8, and n, is 0
(1) The median of the numbers in S is less than 5.
(2) The median of the numbers in S is greater than 1.


Solution:

OPT I: if median n ={...-2,-1,0,1,2,3,4}. thus inSufficient.

OPT II: if median > 1 ==> n={2,3,4...}. thus insufficient.

Taking both options together n={2,3,4} ==> 0Sufficient.
Ans: C

Both together answer the question (C)

Come __ON PG>>>>SSSS.....Guys One more please answer this
If set S consists of the numbers 1, 5, -2, 8, and n, is 0
(1) The median of the numbers in S is less than 5.
(2) The median of the numbers in S is greater than 1.
1)circle C and Like K, lie in a plane XY, If C has center @ origin with radius 1, does like K intercects C

a The intercept of like K>1
b Slope of like K -1/10

2) K Not equal To 0,1 & -1 IS 1/K>0

a 1/k-1>1
b 1/k+1>0



Plz Answe them PG's

1)E--both not sufficient..

2)B--second statement alone is enough...
1/k+1>0 =>1/k>-1 =>kThus, 1/kHowever, the first statement gives us k

1)E--both not sufficient..

2)B--second statement alone is enough...
1/k+1>0 =>1/k>-1 =>kThus, 1/kHowever, the first statement gives us 1/k


Plz Explain The First One...
1)E--both not sufficient..

2)B--second statement alone is enough...
1/k+1>0 =>1/k>-1 =>kThus, 1/kHowever, the first statement gives us k

Slight error in Q no. 2 plz forgive
Actually, statement 1 can also give us the answer
1/k-1>1
=>1/k>2
Thus, 1/k>0.
So, the answer should be C...either statement alone is enough

As for Q no. 1,
equation of the line is
y= -x/10 +c, where c>1....(slope-intercept form)..using both the data
=>10y +x= 10c, c>1
While the equation of the circle is x^2+ y^2 = 1
If the two equations can be solved, it means the line intersects the circle; if they cannot be solved, line does not intersect.
But we cannot say if the equations have a solution, until the value of c is determined.
Given data is insufficient. So, E.
Slight error in Q no. 2 plz forgive
Actually, statement 1 can also give us the answer
1/k-1>1
=>1/k>2
Thus, 1/k>0.
So, the answer should be C...either statement alone is enough

As for Q no. 1,
equation of the line is
y= -x/10 +c, where c>1....(slope-intercept form)..using both the data
=>10y +x= 10c, c>1
While the equation of the circle is x^2+ y^2 = 1
If the two equations can be solved, it means the line intersects the circle; if they cannot be solved, line does not intersect.
But we cannot say if the equations have a solution, until the value of c is determined.
Given data is insufficient. So, E.

Crab Bro,
m sorry but i think for the second question
2) K Not equal To 0,1 & -1 IS 1/K>0

a 1/k-1>1
b 1/k+1>0

only, A is the ans....B is wrong....explanation
1/k+1>0 => 1/k > -1 => -1 1/k can also be -1/2, -1/3 and can be ny positive no...as 1/k can be greater or lesser than zero so op B is not definate
hence only A is the rite ans...
Slight error in Q no. 2 plz forgive
Actually, statement 1 can also give us the answer
1/k-1>1
=>1/k>2
Thus, 1/k>0.
So, the answer should be C...either statement alone is enough

As for Q no. 1,
equation of the line is
y= -x/10 +c, where c>1....(slope-intercept form)..using both the data
=>10y +x= 10c, c>1
While the equation of the circle is x^2+ y^2 = 1
If the two equations can be solved, it means the line intersects the circle; if they cannot be solved, line does not intersect.
But we cannot say if the equations have a solution, until the value of c is determined.
Given data is insufficient. So, E.

Crab Bro,
m sorry but i think for the second question
2) K Not equal To 0,1 & -1 IS 1/K>0

a 1/k-1>1
b 1/k+1>0

only, A is the ans....B is wrong....explanation
1/k+1>0 => 1/k > -1 => -1 1/k can also be -1/2, -1/3 and can be ny positive no...as 1/k can be greater or lesser than zero so op B is not definate
hence only A is the rite ans...

try a tough one...

1. Is n/18 an integer? (1) 5n/18 is an integer. (2) 3n/18 is an integer.

try a tough one...

1. Is n/18 an integer? (1) 5n/18 is an integer. (2) 3n/18 is an integer.

ANs: A
1. 5n/18 is an intgr ==> n is perfectly divisible by 18 because 18 and 5 have no common factors or are co-prime numbers. Hence Opt 1 alone is sufficient.

2. 3n/18 is an intgr ==> 3 is the common factor between 3 and 18 so we cannot be certain if n is completely divisible by 18. SO Opt 2 alone is insufficient.

If ab is not equal to 0, and points (-a,b) and (-b,a) are in the same quadrant of the xy plane, is point (-x,y) in this same quadrant?
(1) xy>0
(2) ax>0