Aptitude - Percentage - Discussion

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.

The unit's digit (or ones digit) of a number is the digit in the farthest right position. It represents how many ones are in the number.

For example:
In the number 345, the unit's digit is 5.
In the number 82, the unit's digit is 2.
In the number 1090, the unit's digit is 0.
So, when looking for numbers with a specific unit's digit, you're checking the last digit of each number.

@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.

@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%.

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.

!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.

@All.

Here is my explanation for the answer.

Let's take initial values as 100%, which means initially the fruit seller had some apples, so I take that as 100%.

Now, if he sells 40% of his apples, he has 60% of the apples remaining.

So, in the question, they have already stated that the seller has 420 apples after selling 40%.

Thus, we have:
60% = 420.
100% = x.

To solve this expression:
x = (420×100)60x = 60(420×100)​.
x = 700x = 700.

Therefore, the answer is 700.

1 to 9 = 2 digit (1,9) =2.
11 to 70 = [digit1-tens digit2-units].
At unit one place suppose I have put 1 there that means I have the choice to
put 6 digits at the tens place = 6 * 1 = 6.
similarily for 9 also = 6 *1 = 6.

The reason we are taking 6 digits is because it will exceed the range that is given.
So, total = 14,
14 = x /100 * 70,
x = 20%.

@Moses Ug.

We can't consider 12 to 18 because the question says in units place of a number it should either have 1 or 9 not in tens place.

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