Since there is no repetition allowed, there are 10 possibilities for the 1st digit, 9 for the 2nd, 8 for the 3rd, and 7 for the 4th. This gives a total of (10)(9)(8)(7) = 5040 four-digit codes.
For all odd digits to be used, there are 5 possibilities for the 1st digit (1,3,5,7,9), 4 for the 2nd, 3 for the 3rd, 2 for the 4th. This gives a total of (5)(4)(3)(2) = 120 codes that only use odd digits.
Therefore there are 5040 - 120 = 4920 codes that do not consist of all odd digits. The probability is 4920/5040 = 41/42.
This is a simple equation:
x - 7 < 14
x < 14 + 7
x < 21
→ Many people think that because there is not "=" sign they don't flip the sign of what in this case is -7. But actually, the symbols "<" and ">" act as the equal sign. This rule doesn't apply to positive number, only negative.
Hope it helped,
BioTeacher101
(If you have any questions, feel free to ask them in the comments)
Answer:
C. 41
Step-by-step explanation:
180 - 81 = 99
99+40 = 139
180 -139 = 41
Answer:
The standard error in estimating the mean = (0.1 × standard deviation of the distribution)
Step-by-step explanation:
The standard error of the mean, for a sample, σₓ is related to the standard deviation, σ, through the relation
σₓ = σ/(√n)
n = sample size = 100
σₓ = σ/(√100)
σₓ = (σ/10) = 0.1σ
Hence, the standard error in estimating the mean = (0.1 × standard deviation of the distribution)