Each pouch has 9 nuggets, each either 7g or 5g.
Key trick: The more 7g nuggets a pouch has, the higher its average weight will be (since the average sits somewhere between 5g and 7g).
So the real question becomes:
"Is the Black pouch's average weight higher than the White pouch's average weight?"That's all we need to figure out.
Statement (2) directly tells us:
Black's average > White's averageThat answers it immediately — Black has more 7g nuggets. ✅
SufficientStatement (1) — A bit indirect
This one says: if you add one 10g nugget to
each pouch,
White's average increases by more than Black's average does.
Here's the logic to understand:
Imagine two groups with different averages, and you add a
heavy new item (10g) to both. The group that started with the
lower average will get pulled up
more, because the 10g nugget is farther above its average, so it has a bigger pulling effect.
(Simple analogy: two students have average test scores of 40 and 60. If both take one more test and score 100 on it, the student with the average of 40 will see their overall average jump up more — because 100 is much farther from 40 than it is from 60.)So:
White's average increased more → this means
White started with the lower average → which means
Black's average was higher.
That's the exact same conclusion as Statement (2)! ✅
SufficientFinal Answer:
DRuss19
A jeweller has a black pouch and a white pouch, and each pouch contains nine gold nuggets. Some of the nuggets weigh 7 grams and the remaining nuggets weigh 5 grams. Does the black pouch contain a greater number of 7 gram nuggets than the white pouch?
1) If one 10 gram gold nugget were added to each pouch, the average (arithmetic mean) weight of a nugget in the white pouch would increase by a greater amount than would the average (arithmetic mean) weight of a nugget in the black pouch.
2) The average (arithmetic mean) weight of a nugget in the black pouch is greater than the average (arithmetic mean) weight of a nugget in the white pouch.