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leva [86]
3 years ago
14

How many 7 digit phone numbers are there assuming the first digit can't be a 0 or a 1?

Mathematics
1 answer:
Anettt [7]3 years ago
7 0
The first digit can be any one of the numbers 2-9 That a total of 8 numbers.

The next 6 digits can be any permutation of 6  from the numbers  0 to 9.
(10 numbers)

nPr  =  n! / r!

so here we have  10P6  = 10! / 6!  =  10*9*8*7  =  5040

So final answer  is 8 * 5040 = 40,320
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{(-1, 4), (-1, 9), (-1, 15), (-1, 0)}
marishachu [46]

Answer:

domain is -1

range is {4, 9, 15, 0}

function: not a function

6 0
3 years ago
The graph below shows the average daily temperatures on January 1 from 1900 to 1934 for city A.
kipiarov [429]

Answer:

25 years

Step-by-step explanation:

Solution:-

- Data for the average daily temperature on January 1 from 1900 to 1934 for city A.

- The distribution X has the following parameters:

                    Mean u = 24°C

                    standard deviation σ = 4°C

- We will first construct an interval about mean of 1 standard deviation as follows:

  Interval for 1 standard deviation ( σ ):                                    

                    [ u - σ , u + σ ]

                    [ 24 - 4 , 24 + 4 ]

                    [ 20 , 28 ] °C

- Now we will use the graph given to determine the number of years the temperature T lied in the above calculated range: [ 20 , 28 ].

           T1 = 20 , n1 = 2 years

           T2 = 21 , n2 = 3 years  

           T3 = 22 , n3 = 2 years

           T4 = 23 , n4 = 4 years  

           T5 = 24 , n5 = 3 years

           T6 = 25 , n6 = 3 years  

           T7 = 26 , n7 = 5 years

           T8 = 27 , n8 = 2 years

           T5 = 28 , n9 = 1 years

- The total number of years:

               ∑ni = n1 + n2 + n3 + n4 + n5 + n6 + n7 + n8 + n9

                     =  2 + 3 + 2 + 4 + 3 + 3 + 5 + 2 + 1

                     = 25 years          

3 0
3 years ago
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<span>What is the only way to sober up?<span>stuff like cold showers, fresh air, or chewing gum works but time is the only</span></span>
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3 years ago
In a music competition, a participant has to score a total of at least 40 points in the first four rounds combined to move on to
MAXImum [283]
4+3p≥40
He needs to have 40 or more to get to the finals so 4+3p has to be 40 or more
7 0
3 years ago
What is the answer for x+b over 4
Lady_Fox [76]
X/4 + b/4
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