Aptitude - Percentage - Discussion

@Lobsang.

Because, They didn't ask about us anyone's Square.

They just told you to find how many no belongs in 1to70 That last digit should come only 1 and 9. Like 01, 09, 11, 19, 21, 29. 69.

Hope you understood.

@All.

Here, they have incorrectly missed the number range from 11-20, which includes 10 numbers (not 2). The ranges from 1-70, which include a 1 or 9. 11, 12, 13, 14, 15, 16, 17, 18, 19 = 10. All from 1 - 70 have 2. Therefore the total sum = 22/70 which equates to 31%.

Numbers from 1 to 70.
Having 1 or 9 in unit digits,
1 seven times and 9 seven times,
14/70 * 100 = 20.

Why shouldn't we consider 10, 11, 12, 13, 14, 15, 16, 17, 18 as they have 1 in its unit?

Does 12 up to 18 have a digit 1 or not?

Anyone, please clarify.

!All.

Here, They asked 1 or 9, why all answers are included both 1 and 9, if we considered 1 or 9 only the percentage should be 10%.

Correct me, if I'm wrong.

To find the percentage of numbers from 1 to 70 that have 1 or 9 in the unit's digit, we first identify all such numbers.

Numbers with 1 in the unit's digit:
1, 11, 21, 31, 41, 51, 61

Numbers with 9 in the unit's digit:
9, 19, 29, 39, 49, 59, 69

Each set has 7 numbers.

Combining both sets, we have:
1, 9, 11, 19, 21, 29, 31, 39, 41, 49, 51, 59, 61, 69,
In total, there are 14 numbers from 1 to 70 with either 1 or 9 in the unit's digit.

Percentage = ( Number of desired numbers)/Total numbers × 100.
Percentage = (14/70)× 100 = 20%.
Therefore, 20% of the numbers from 1 to 70 have either 1 or 9 in the unit's digit.

1-10 = 2 available 1,9.
11-20 = 2 available 11,19.
21-30 = 2 available 21,29.
31-40 = 2 available 31,39.
41-50 = 2 available 41,49.
51-60 = 2 available 51,59.
61-70 = 2 available 61,69.
Q1/q2 ×100.
= 14/70 ×100
= 20.

I think the total numbers are 15 because here, the number 10 is missed.

10 also have the number 1.

@All.

Here, In 1s digit there are 14 numbers with 1 and 9.

So 70% = 100.
14% = x.
Cross multiply.
70 (x) =14 (100).
X = 1400/70.
X = 20.