Data Sufficiency

Hi guys,

Can you help me with these questions, please?

All OAs will be posted. Thanks

Q1
For the students in class A, the range of their heights is r centimeters and the greatest height is g centimeters. For the students in class B, the range of their heights is s centimeters and the greatest height is h centimeters. Is the least height of the students in class A greater than the least height of the students in class B?

(1) r<s
(2) g>h

Q2
Did it take Pei more than 2 hours to walk a distance of 10 miles along a certain trail? (1 mile = 1.6 km, rounded to the nearest tenth).

(1) Pei walked this distance at an average rate of less than 6.4 km phr
(2) On average, it took Pei more than 9 min per km to walk this distance.

First one is clear to me, using ST = D; second can be any time, since it says 'more than'?? this is what slightly confuses me.

Q3
What is the value of 5x^2 + 4x - 1?

(1) x(x + 2) = 0
(2) x = 0

why is (1) not sufficient?

Q4
Is |x| > |y|?

(1) x^2 > y^2
(2) x > y

what theory would you use here?




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