Logic
A series of cards is marked. On one side of the card there is a
letter. On the other side of the card there is a number (single
digit). So, you might find an A or a B on one side, and a 0 or a 1 on
the other side.
There is an hypothesis: if the letter is a vowel (A, E, I, O or
U), then the digit on the other side of the card is an EVEN number.
There is a pile of cards on the floor, all scrambled. Some show
letters like A, B, E, F, and some show digits like 1, 4, 7, 8.
It will cost you $10 to buy a card in order to test the hypothesis
stated above. To be sure that the hypothesis is correct, which cards
do you have to buy?
The US Post Office used to let you mail envelopes that were not
sealed at a lower rate than letters that were sealed. A pile of
envelopes were stamped. Some envelopes were sealed, and others were
not sealed. Suppose that, if the envelope were sealed, then it had to
have a $0.12 stamp. If it were NOT sealed, it COULD have as little as
a $0.09 stamp. There was a pile of envelopes on the floor. Some had
$0.12 stamps, and others $0.09 stamps. Some were sealed, and others
were not sealed. Which envelopes did you need to check to be sure
that the sealed envelopes had at least $0.12 stamps?
If the rat is fat, this it's serum lipids will be high. You have
to test this hypothesis. You have two kinds of data available. One
is, for one bunch of rats, measures of their weight. The other, for a
different bunch of rats, is a list of their serum lipid
concentrations. You can do two kinds of experiments for any rat --
weigh the rat, and/or measure its lipid concentrations. SO, you can
measure the serum lipids for a rat whose weight you already know, and
you can weigh a rat whose serum lipids you already know. What
experiments do you need to perform in order to test the
hypothesis.
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