Aptitude - Problems on Numbers - Discussion

Discussion Forum : Problems on Numbers - Data Sufficiency 1 (Q.No. 2)
Directions to Solve

Each of the questions given below consists of a statement and / or a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statement(s) is / are sufficient to answer the given question. Read the both statements and

  • Give answer (A) if the data in Statement I alone are sufficient to answer the question, while the data in Statement II alone are not sufficient to answer the question.
  • Give answer (B) if the data in Statement II alone are sufficient to answer the question, while the data in Statement I alone are not sufficient to answer the question.
  • Give answer (C) if the data either in Statement I or in Statement II alone are sufficient to answer the question.
  • Give answer (D) if the data even in both Statements I and II together are not sufficient to answer the question.
  • Give answer(E) if the data in both Statements I and II together are necessary to answer the question.

2.

What is the two-digit number?

I. 

The difference between the two digits is 9.

 II. 

The sum of the digits is equal to the difference between the two digits.

I alone sufficient while II alone not sufficient to answer
II alone sufficient while I alone not sufficient to answer
Either I or II alone sufficient to answer
Both I and II are not sufficient to answer
Both I and II are necessary to answer
Answer: Option
Explanation:

Let the tens and unit digits be x and y respectively. Then,

 I. x - y = 9.

II. x + y = x - y.

From I and II, we get x - y = 9 and x + y = 9.

On solving, we get x = 9 and y = 0.

Required number is 90.

Thus, both I and II are needed to get the answer.

Correct answer is (E).

Discussion:
22 comments Page 3 of 3.

Mukesh rai said:   1 decade ago
Here we have to find out the 2 digits no. whose difference is 9 and this is possible when one digit is 9 and other is 0

Here we have only option that the no. is 90

V S S Ranganadh P said:   1 decade ago
In the question
The difference between the two digits is 9
only possible for 0 and 9
The possible ways are {(0,9)}
{(10,1),(11,2),...} this set is not possible for single sigit no.s
So, number should be 90 or 09
09=9( not a 2 digit number)
then 90 is the number.
Option I is sufficient


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