Answer:
c) 50
Step-by-step explanation:
We have been given that the mean life of a particular brand of light bulb is 1200 hours. About 95% of this brand of bulbs will last between 1100 and 1300 hours.
We will use z-score formula to solve our given problem.
, where,
,
,
,

We know that 95% of data points lies within two standard deviation of mean, so 1100 will correspond to a z-score of -2 and 1300 will correspond to a z-score of 2.




We can use sample score 1300 and get same answer as:




Therefore, the standard deviation of the light bulbs’ life is 50 years.
17
85/17 is 5 and 51/17 is 3
Answer:
1) 9:14
2)4:1
Step-by-step explanation:
You have to have all of the teachers compared to all of the adults (teachers included)
You have to simplify 12:3 and you get 4:1.
Answer:
5+9v
Step-by-step explanation:
Answer: you alredy solved it
Step-by-step explanation: