RT = BT = 75
This is because she used the same angle from point C to mark point B, thus creating a symmetric right triangle.
Triangle BCT = Triangle RCT
A keypad at the entrance of a building has 10 buttons labeled 0 through 9. What is the probability of a person correctly guessing a 9-digit entry code if they know that no digits repeat?
Answer:
the probability of a person correctly guessing a 9-digit entry code if they know that no digits repeat is 0.1
Step-by-step explanation:
We know that probability= number of required outcomes /number of all possible outcome.
From the given information;
the number of required outcome is guessing a 9-digit = 1 outcome
the number of all possible outcome = ¹⁰C₉ since there are 10 numbers and 9 number are to be selected.
Since there are only 9-digit that opens the lock;
the probability of a person correctly guessing a 9-digit entry code is
P = 0.1
If you would like to know the mean of the data set, you can calculate this using the following steps:
The <span>mean </span><span>of the data set is the sum of all the data values divided by the number of these values.
</span><span> </span>
<span>12, 17, 16, 10, 20, 13, 14, 14, 12, 12, 19, 18
</span>
<span>12 + 17 + 16 + 10 + 20 + 13 + 14 + 14 + 12 + 12 + 19 + 18 = 177
</span>the number of data values: 12
177 / 12 = 14.75
The correct result would be B. 14.75.
Not sure how to give a hint without blatantly giving the answer but...
Consider an n - digit number in base b.
That is N=an−1an−2.....a0=∑k=0akbk
N
=
a
n
−
1
a
n
−
2
.
.
.
.
.
a
0
=
∑
k
=
0
a
k
b
k
Note aka
k
<
b
so we can easily show NN
<
b
n
(may have to repeat and argue inductively.
And presumably to be n - digit than an−1≠0
a
n
−
1
≠
0
so N≥bn−1
N
≥
b
n
−
1
.
So we have: every n digit number is between bn−1
b
n
−
1
inclusively and bn
b
n
exclusively. This should be blindingly obvious to us if b=10
b
=
10
.
So... that's a really important and fundamental result. Remember and use it.
