In DS questions, you have to be very clear on the information you've been given (what do you KNOW for sure vs. what are the possibilities).
In this prompt, we have a serious lack of information. We're asked for the total value of Company H's stock, but we're given no information to start off with.
Fact 1: Investor P owns 1/4 of the shares.
This tells us nothing about the value of those shares, nor does it tell us how many people own the remaining 3/4 of the shares, so there's no way to determine the total value of the stock.
Fact 1 is INSUFFICIENT.
Fact 2: The value of Investor Q's shares of Company H's stock is $16,000.
This doesn't tell us what fraction of the total shares are owned by Investor Q, so there's no way to determine the total value of the stock.
Fact 2 is INSUFFICIENT.
Combined, we know...
Investor P owns 1/4 of the shares.
Investor Q owns an unknown fraction of the shares, which are valued at $16,000
Since we don't know if Investor Q owns 3/4 of the shares or less than 3/4 of the shares (there MIGHT be other investors), there's no way to use the value of the shares that he does own to figure out the total value of the stock.
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