Answer:
atleast 385
Step-by-step explanation:
Given that an electrical power company is looking to expand into a new market. Before they commit to supplying the new area with electricity, they would like know the mean daily power usage for homes there.
Population std deviation = 
Sample size =
STd error of sample mean = 
Margin of error for 95% would be Critical value ( std error)
Here since population std dev is known we can use Z critical value= 1.96

Sample size should be atleast 385
Answer:
136 mm²
Step-by-step explanation:






A = 136
You put all x on left side and numercial on the right side
13x-12x = 4+4
x = 8
16 days is a part of 3 weeks, so $2500 x 3 = $7500. if he spends $380 per day for 16 days, that equals $6080. so subtract $6080 from $7500 and you get $1420 (how much he has left)
Make a proportion 20 miles/4 hours= 75miles/x. cross multiply gives you 20x=300. this will give you x = 15 hours