Exercise 15.2

1. Use deductive reasoning to answer the following:

i. Human beings are mortal. Jeevan is a human being. Based on these two statements, what can you conclude about Jeevan?

(i) Based on the two statements we can conclude that Jeevan is

ii. All Telugu people are Indians. X is an Indian. Can you conclude that X belongs to Telugu people?_

(ii) , x could be from any other state of India other than Andhra Pradesh and Telangana.

iii. Martians have red tongues. Gulag is a Martian. Based on these two statements, what can you conclude about Gulag?_

(iii) Based on the two statements we can conclude that Guly has a tongue

iv. What is the fallacy in the Raju's reasoning in the cartoon below?_

(iv) All smart people are presidents. There are a lot of smart people in different fields or different line of work all of them be presidents.

2. Once again you are given four cards. Each card has a number printed on one side and a letter on the other side. Which are the only two cards you need to turn over to check whether the following rule holds?

"If a card has a consonant on one side, then it has an odd number on the other side."

Sol:

Given rule: "If a card has consonant on one side, then there is an odd number on the other side"

We need to check cards and

Reason: {.reveal(when="blank-2")}1. We need to check B because if it has an number on the other side, the rule would be broken

2. We need to check 8 because if it has a on the other side, the rule would be broken

∴ The only two cards we need to turn over are B and 8 to verify the rule

3. Think of this puzzle: What do you need to find a chosen number from this square?

Four of the clues below are true but do nothing to help in finding the number.

Four of the clues are necessary for finding it.

Here are eight clues to use:

a. The number is greater than 9.

b. The number is not a multiple of 10.

c. The number is a multiple of 7.

d. The number is odd.

e. The number is not a multiple of 11.

f. The number is less than 200.

g. Its ones digit is larger than its tens digit.

h. Its tens digit is odd.

Sol:

From the given clues we can conclude that the answer is

Analysis of each clue: "Yes" if helps else "No"

a. - The number clearly has more than one digit

b. - The only multiple of 7 that is also a multiple of 10 is 70

c. - It eliminates all numbers that are not multiples of 7

d. - Being an odd number eliminates many possibilities

e. - The multiple of 7 and 11 is 77, but both digits are equal

f. - Too broad a range to be useful

g. - Eliminates numbers where ones digit is not larger than tens digit

h. - Helps identify the correct number (35)

∴ The four clues that help in finding the number are: , , , and