Answer:
4a - 20b - 3c
Step-by-step explanation:
6a - 5b - 8c - 15b - 2a + 5c
= 4a - 20b - 3c
Answer with explanation:
Given : The age that children learn to walk is normally distributed with
and
.
Let x be the age that children learn to walk .
B) Using formula 
n= 19
For x= 11.5

For x= 12.5

Then, by using the z-value table , for the 19 people, the probability that the average age that they learned to walk is between 11.5 and 12.5 months old will be :-

Hence, for the 19 people, the probability that the average age that they learned to walk is between 11.5 and 12.5 months old = 0.9707
C. Using formula 
For x= 11.5

For x= 12.5

Then, by using the z-value table , the probability that the average age that they learned to walk is between 11.5 and 12.5 months old will be :-

Hence, the probability that the average age that they learned to walk is between 11.5 and 12.5 months old = 0.3829