Answer
given,
installed electric lamp = 2000
average life = 1000 hrs
standard deviation = 200 hrs
a)
let after p hors 10% bulb fails ,
P(X<p) = 0.10
from Normal distribution table,
P(Z<-1.28) = 0.10
on comparing
x = -1.28 x 200 + 1000
x = 744 hours
b) P( 900 < X < 1300) =
=
= P(-0.5 < Z < 1 .5)
= P(Z<1.5) - P(Z<-0.5)
= 0.93319 - 030854
= 0.62465
lamps may be expected to fail between 900 and 1300
= 0.62465*2000
= 1249.3
= 1249 (approx)
Answer:
(n/3) + 4 ≤ 9
Step-by-step explanation:
"Four more than the quotient of a number and 3" is represented by
n/3 + 4
and this quantity is "at most 9:"
And so we get:
(n/3) + 4 ≤ 9
D + 3n = 1 Subtract d from both sides
3n = 1 - d Divide both sides by 3
n =
Answer:
this is the question of mathematics
so you should know formulas
after then only it can be solved..
without formula it cannot be solved ..
Answer:
5 miles.
Step-by-step explanation:
Because area is just length times width so in that sense 20/4 is 5 :)