Answer:
Modification has not reduced the number of accidents.
Step-by-step explanation:
A B C D E F G H
Before modification 5 7 6 4 8 9 8 10
After modification 3 7 7 0 4 6 8 2
Difference -2 0 1 -4 -4 -3 0 -8
Mean of differences
Standard deviation of differences =
Formula of paired t test :
Df = n-1 = 8-1 =7
t critical> t calculated
So, We failed to reject null hypothesis
Hence modification has not reduced the number of accidents.
Using permutations, it is found that there are 12 ways to pick a sequence of two different letters of the alphabet that appear in the word Crab .
The order in which the letters appears is important, as for example, ab is a difference sequence than ba, hence the <em>permutation formula</em> is used.
Permutation formula:
The number of possible permutations of x elements from a set of n elements is given by:
In this problem, 2 letters are picked from a set of 4, hence:
There are 12 ways to pick a sequence of two different letters of the alphabet that appear in the word Crab .
For more on permutations, you can check brainly.com/question/24905801