Answer:
4.924 years
Step-by-step explanation:
Lets denote X the lifetime of a tv tube (In years). X has distribution 
, with 
unknown.
We know that P(X < 4) = 0.2. Using this data, we can find the value of throught standarization.
Lets call 
the standarization of X. Z has distribution N(0,1), and its cummulative function, 
is tabulated. The values of can be found in the attached file.
The value q such that 
doesnt appear on the table. We can find it by using the symmetry of the normal density function. The opposite of q, -q must verify that 
, hence -q must be equal to 0.84. Thus, q = -0.84
But this value of q should match with the number 
, so we have
Thus, the expected lifetime of TV tubes is 4.924 years.
I hope this works for you!
In order to study geometry logically, it will be important to understand key mathematical properties and to know how to apply useful postulates and theorems. a postulate is a proposition that has not been proven true but is considered to be true on the basis for mathematical reasoning.
12.99+2.50=15.49
20.00-15.49= 14.51
X=CD
Y=Birthday card
Z=total
L=money left
X+Y=Z
20-z=L
(I hope this helps at least a little?)
Answer:
hello : 256 words
Step-by-step explanation:
2 minutes and 30 = (2×60)+30=150seconds
4 minutes = 4 ×60 = 240 seconds
150seconds →160 words
240 seconds → x ?
x = (160×240) / 150 = 38400/150= 256 words
