i think there was a typo in answer B because they both say 1991 :-/

hey money9111, look at the option B. Though it says 1991- one part deals with consumption while the other with the amount mined.

(A) In Country Q, more coal was mined in 1990 than
was mined in 1991. [we have no information about this statement from the stimulus. Eliminated!]

(B) In Country Q, the amount of coal consumed in
1991 was greater than the amount of coal
mined in 1991. [Correct! we know that the tally was less in 1991, so it means the consumption must be greater than the amount mined. remember we cannot take any option that compares 2 years coz we have no information separately about any one.]

(C) In Country Q, the amount of coal consumed in
1990 was greater than the amount of coal
consumed in 1991. [information is not stated. it depends on the amount of coal mined and also on the consumption. Eliminated]

(D) In Country Q, the amount of coal consumed in
1991 was greater than the amount of coal
consumed in 1990. [same as C. Eliminated!]

(E) In Country Q, more coal was consumed during
the first half of 1991 than was consumed
during the first half of 1990. [same as C. Eliminated!]

Hope this helps!

whoops... i think i assumed that if they meant to make that comparison they would have said ....in the same year

gmatnmein2010 wrote:Each December 31 in Country Q, a tally is made of
the country's total available coal supplies-that is,
the total amount of coal that has been mined
throughout the country but not consumed. In 1991
that amount was considerably lower than it had been
in 1990. Furthermore, Country Q has not imported or
exported coal since 1970.
If the statements above are true, which one of the
following must also be true on the basis of them?
(A) In Country Q, more coal was mined in 1990 than
was mined in 1991.
(B) In Country Q, the amount of coal consumed in
1991 was greater than the amount of coal
mined in 1991.
(C) In Country Q, the amount of coal consumed in
1990 was greater than the amount of coal
consumed in 1991.
(D) In Country Q, the amount of coal consumed in
1991 was greater than the amount of coal
consumed in 1990.
(E) In Country Q, more coal was consumed during
the first half of 1991 than was consumed
during the first half of 1990.
the oa as per the set i have is
OA B

a littlebit of eqn:

We need a statement where we can confirmed that the difference (production-consumption) for 1990 is higher than that of 1991 i.e. diff for (1990)> dif for (1991).

A says that more coal was mined in 1990 than in 1991. But if the consumption was also more than that of 1991 then the difference could be possibly lower than that of 1991.

C says that consumption of 1990 > consumption of 1991. But still no production figures are given. There could be a possibility that production for both the years was same. In that case diff (1990)< diff (1991).

D says that consumption(1991)> consumption(1990). Here again the production figures are not provided. What if production(1991) was much higher than that of production(1990). This would mean diff (1990)< diff (1991).

E is totally out of scope.

Hence B is true

in other words
as there was no import or export & if consumption(1991)>production(1991) then that implies that diff of prod and cons for (1991) is less than <0 i.e. -ve,

If diff is -ve & no imports were made then the extra coal came from the last years left over stock i.e. diff or inventory of (1990). And if there were stocks left unconsumed in 1990 then that means that inventory (1991)>0 i.e. +ve.

Now, inventory (1990)>0 & inventory (1991)<0. Therefore, inventory (1990)>inventory (1991). Hence, Proved. There is no other way in which Country Q consumed more than it produced.

HTH
And a good Q too