Please help is and example of ?
2 answers:
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Answer:
Speed of river's current = 5 mph
Step-by-step explanation:
Let 'd' be the distance covered
Let x be the speed of the rivers current
Speed upstream = 15-x
speed downstream = 15+x
Time = distance / speed
time upstream =
time downstream =
the ferry trip upstream takes twice as long as its return trip downstream
=
divide both sides by d
=
cross multiply
Add 2x on both sideds
subtract 15 from both sides and divide by 3
x=5
Speed of river's current = 5 mph
This can be solved using a system of equations.
Subtract y from both sides.
Substitute:
Subtract 80 from both sides:
Divide both sides by 5:
Substitute.
Subtract y from both sides.
Substitute:
Subtract 80 from both sides:
Divide both sides by 5:
Substitute.
Answer:
Step-by-step explanation:
Variance is the sum of squares of all items x from mean. i.e
Variance =
Being the sum of squares variance can never be negative irrespective of mean being negative.
Std deviation is the square root of variances. This will thus be less than variance if variance >1 other wise std deviation will be bigger than variance.
Hence option d is right.