Answer: 37
Step-by-step explanation:
Given : Significance level : 
Critical value : 
margin of error : E= 1 mile per gallon
Population standard deviation:
miles per gallon.
We know that when the population standard deviation is known then the formula to find the sample size is given by :

[Round to the next whole number.]
Hence, the required number of automobiles should be used in the test = 37
Going upstream: 432 km / 6 hours = 72 km/h
Going downstream: 384 km / 4 hours = 96 km/h
Going upstream against the current means that the effective speed is:
r_boat - r_current = 72
Meanwhile, going downstream with the current means;
r_boat + r_current = 96
Adding both equations (to cancel out r_current) gives:
2r_boat = 72 + 96
r_boat = 84 km/h
Substituting back into one of the original equations: r_current = 12 km/h.
-12ab+7a power of 2 +a 11
Answer:
The height of the tree=8.42 m
Step-by-step explanation:
We are given that
Height of Joshua, h=1.45 m
Length of tree's shadow, L=31.65 m
Distance between tree and Joshua=26.2 m
We have to find the height of the tree.
BC=26.2 m
BD=31.65m
CD=BD-BC
CD=31.65-26.2=5.45 m
EC=1.45 m
All right triangles are similar .When two triangles are similar then the ratio of their corresponding sides are equal.


Substitute the values



Hence, the height of the tree=8.42 m
Answer:
16
Step-by-step explanation:
there are four gallons
1=4 quartz
so u multiply
4 x 4 = 16
4=16