All three sentences are comparing different attributes of the three dogs. Although we know that Riley is stronger than Kelsey, we do not have any comparison of their speed except in the third sentence. If we only know that the first two sentences are true, the truthfulness of the third sentence is uncertain.

Let's place each child on a spectrum based on how many stuffed animals each has. The child with the most stuffed animals will be placed on the extreme left side of the spectrum and the child with the fewest stuffed animals will be placed on the extreme right side of the spectrum. From Sentence 1, we know that Shelley has more stuffed animals than Bert, so Shelley should be placed on the left, and Bert on the right of the spectrum.

MOST                            FEWEST

Shelley          --             Bert

From Sentence 2, we know that Bert has more stuffed animals than Tanya, so Tanya should be placed to the right of Bert on the spectrum.

MOST                            FEWEST

Shelley    --    Bert   --    Tanya

Looking at the spectrum, we can now tell that Sentence 3 is true: Tanya has fewer stuffed animals than Shelley.

Let's arrange the three people on a spectrum: the person that has read the most books goes on the extreme left and the person that has read the fewest books goes on the extreme right. From Sentence 1, we know that Jeremy has read more books than Leah.

MOST                    FEWEST

Jeremy       --        Leah

From Sentence 2, we know that Daniel has read more books than Jeremy, so Daniel should be placed to the left of Jeremy on the spectrum.

MOST                    FEWEST

Daniel -- Jeremy -- Leah

This means that the Sentence 3 is true: Daniel has read more books than Leah.

There is not enough information given in the first two sentences to determine if Selina loves the color red. We know that she hates pastel colors and that pink is a pastel color, therefore, Selina hates the color pink. Although red is not a pastel color, there is nothing stated in the first two sentences about colors Selina likes. Consequently, it is uncertain whether she loves the color red.

Based on the information from the first two sentences, the third sentence must be false. Sentence 1 states that Magali will take her vacation "as soon as" she has earned the money. This implies that Magali will not wait, but will go on vacation immediately. Sentence 2 states that Magali is working an extra job to earn the money more quickly. This sentence also implies that Magali has not earned enough money yet. Consequently, the third sentence stating that Magali has earned enough money to go on vacation must be false.

Since we only know that the first two sentences are true, the truthfulness of the third sentence is uncertain. The first two sentences compare the popularity of peanut butter and jelly sandwiches with tuna sandwiches. Roast beef is never mentioned in the first two sentences, so we can not determine if it is the most popular or not.

Let’s use symbols from math to help us understand this.  “Greater than” (>) will mean “more frightening,” and “less than” (<) will mean “less frightening.”

(1) Gremlins are more frightening than ogres: gremlins > ogres

(2) Skeletons are less frightening than ogres: skeletons < ogres

This could be rewritten as: ogres > skeletons

All together, we can say:

gremlins > ogres > skeletons

Therefore, it is indeed the case that gremlins are more frightening than skeletons.

Let’s use symbols from math to help us understand this. “Greater than” (>) will mean “is stranger than,” and “less than” (<) will mean “is more normal than.”

(1) Egbert is a stranger name Dilbert: Egbert > Dilbert

(2) Dilbert is more normal of a name than Ethelbert: Dilbert < Ethelbert

This could be rewritten: Ethelbert > Dilbert

Notice that these two statements only tell us that Dilbert's name is more normal than Egbert and than Ethelbert.  This does not tell us anything about the relationship between Egbert and Ethelbert.