Answer:
0.969
Step-by-step explanation:
Given that:
Mean lifetime (m) = 520 hours
Variance = 900
Hence, standard deviation (s) = √900 = 30
Probability that bulb will last for at most 576 hours
X ≤ 576
Obtain the standardized score :
Using the relation :
Zscore = (x - m) / s
Zscore = (576 - 520) / 30
Zscore = 56 / 30
Zscore = 1.867
P(Z ≤ 1.867) : using the z probability calculator ;
P(Z ≤ 1.867) = 0.96905
Hence, P(Z ≤ 1.867) = 0.969
1. Three consecutive integers: x, x+1, x+2, such that:
x + x + 1 + x + 2 = 120
3 x + 3 = 120
3 x = 117
x = 117:3= 39
The integers are: 39,40,41.
2.
x + x + 2 = x +1 +21
2 x - x = 22 - 2
x = 20
The integers are: 20,21,22.
3. Four consecutive even integers: x, x+2, x+4, x+6
4 ( x + x + 2 ) = 7 (x + 6 ) - 8
8 x + 8 = 7 x + 42 - 8
8 x - 7 x = 34 - 8
x = 26
The integers are: 26, 28, 30 , 32.
