Unit 4 Excercise

1. Write each of the following statements in the form "if p, then q" in English.   (Hint: Refer to the list of common ways to express implications listed in this section.)

  1. The newspaper will not come if there is an inch of snow on the street.
  2. It snows whenever the wind blows from the northeast.
  3. That prices go up implies that supply will be plentiful.
  4. It is necessary to read the textbook to understand the materials of this course.
  5. For a number to be divisible by 3, it is sufficient that it is the sum of three consecutive integers.
  6. Your guarantee is good only if you bought your TV less than 90 days ago.

2. Write each of the following propositions in the form "p if and only if q" in English.

  1. If it is hot outside you drink a lot of water, and if you drink a lot of water it is hot outside.
  2. For a program to be readable it is necessary and sufficient that it is well structured.
  3. I like fruits only if they are fresh, and fruits are fresh only if I like them.
  4. If you eat too much sweets your teeth will decay, and conversely.
  5. The store is closed on exactly those days when I want to shop there.


Answers for these exercises