What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?
a)
1
b)
14
c)
20
d)
21
Correct answer is 'C'. Can you explain this answer?

Question

What percentage of numbers from 1 to 70 have 1 or 9 in the unit's digit?a)1b)14c)20d)21Correct answer is 'C'. Can you explain this answer?

Answer

1,9,11,19,21,29,31,39,41,49,51,59,61,69 out of 1 to 70 so 14/70*100=20%

Answer

The numbers are=1,9,11,19,21,29,31,39,41,49,51,59,61,69
total numbers containing 1 and 9 = 14
total number of digits = 70
percentage of numbers = 14/70×100
= 20%

Answer

To find the percentage of numbers from 1 to 70 that have 1 or 9 in the units digit, we need to determine how many numbers in that range have a units digit of 1 or 9.

Identifying the numbers with units digit 1 or 9:
We can start by listing all the numbers from 1 to 70 and identifying the numbers with units digit 1 or 9:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70

From this list, we can see that the numbers with units digit 1 are: 1, 11, 21, 31, 41, 51, 61, and 71 (which is not within the range of 1 to 70).

The numbers with units digit 9 are: 9, 19, 29, 39, 49, 59, and 69.

Counting the numbers with units digit 1 or 9:
We can count the numbers with units digit 1 or 9 by counting the numbers in each list separately and adding them together.

There are 8 numbers with units digit 1 and 7 numbers with units digit 9.

Calculating the percentage:
To find the percentage, we divide the count of numbers with units digit 1 or 9 by the total count of numbers from 1 to 70 and multiply by 100.

Total count of numbers from 1 to 70 = 70.

Percentage = (count of numbers with units digit 1 or 9 / total count of numbers) * 100
= ((8 + 7) / 70) * 100
= (15 / 70) * 100
≈ 21.43

Therefore, the percentage of numbers from 1 to 70 that have 1 or 9 in the units digit is approximately 20%.

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