Aptitude - Problems on Numbers - Discussion

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

Each of the questions given below consists of a question followed by three statements. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.


2.

What is the two-digit number?

I. 

Sum of the digits is 7.

II. 

Difference between the number and the number obtained by interchanging the digits is 9.

 III. 

Digit in the ten's place is bigger than the digit in the unit's place by 1.

I and II only
II and III only
I and III only
All I, II and III
None of these
Answer: Option
Explanation:

Let the tens and units digit be x and y respectively.

  I. x + y = 7.

 II. (10x + y) - (10y + x) = 9       x - y = 1.

III. x - y = 1.

Thus, I and II as well as I and III give the answer.

Correct answer is (E).

Discussion:
26 comments Page 1 of 3.

Laxmi said:   1 month ago
But by statement 2 we can't decide which is larger right (xy or yx).

So, I think the answer should be I and III only.

Anbumani said:   3 months ago
I. x + y = 7.
III. x - y = 1.
By Adding I and III,
Then 2x = 8 => x = 4,
And y = 3.

Mithra said:   4 months ago
Let the digits be xy.
x + y = 7,
x + x + 1 = 7
x = 3
y = 4
On interchanging 43-34 = 9.
Then option 1 and 3 are helpful,
Thus option C.

Shayantan Kabiraj said:   11 months ago
D is the correct answer.

Because with only I and II, both 34 and 43 are possible answers.
With only I and III, 43, 52, 61 and 70, all are correct.
Only with I, II and III do we get a single answer, and that is 43.

Sumanth Nakirikanti said:   1 year ago
If both options A and C are correct why would you mark option E.

Abirami said:   2 years ago
Can anyone explain the second statement, how do we get 9? Please explain to me.

Chetna said:   3 years ago
D should be the correct answer. I mean 43 is the only possibility such that the sun is 7 and the difference is 1.

So,it's D.
(3)

RAHUL robin said:   7 years ago
The Correct option will be C.
(1)

Charanya said:   7 years ago
I think its option A. We get answer by I and II only.

Rutuja kapadnis said:   8 years ago
Answer is E.

Eg. 99 (99-99)=0 nd 9=9.


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