Let x be rate of boat in still water
let y be rate of current
we use this equation to relate quantities:
distance = speed · time
we have two unknowns so we might need to create a system of equationss
upstream:
speed (in km/h) = x - y
(we get speed of boat then subtract the current's speed from it since current is going against boat direction)
time = 3 hours
distance = 144 km
downstream:
speed (in hm/h) = x + y
(we get speed of boat then add the current's spd from it since current is going against boat direction)
time = 2 hours
distance = 144 km (same distance upstream and downstream)
using distance = speed times time
for upstream
144 = 3(x-y)
144 = 3x - 3y
for downstream
144 = 2(x+y)
72 = x + y
system of eqns:
144 = 3x - 3y
72 = x + y
solve by substitution: move 72 = x + y into x = 72 - y and subst into other equation for x
144 = 3(72 - y) - 3y
144 = 216 - 3y - 3y
144 = 216 - 6y
144 - 216 = -6y
-72 = -6y
y = 12 km/h
Use x = 72 - y to find x with y = 12: x = 72 - 12 = 60 km/h
rate of boat in still water is 60 km/h
rate of the current is 12 km/h
The first sampling method is Convenient Sampling. It is biased sampling and it is not representative of a random sample.
The second sampling method is Systematic Sampling. If this method of sampling is drawn from the population, it is an efficiently randomized sampling method.
Let us review the given answers.
1. Both samples should be exactly the same.
INCORRECT
2. Neither sample will be representative.
Because the second sampling method can be random, this answer is
INCORRECT.
3. The first sampling method, ..., is the most representative,
INCORRECT
4. The second sampling method, ..., is the most representative.
CORRECT
Answer:
Step-by-step explanation:
The scale factor described denotes a reduction operation. The missing dimension is given by simple rule of three:
Answer:
Step-by-step explanation:
A motorcycle has an initial speed of u m/s. It accelerates to a speed of 1.2u in 10 seconds
V = U + at
1.2u = u + a*10
=> a = 0.02u
S= ut + (1/2)at²
Distance in 1st 10 secs
S = u(10) + (1/2)(0.02)(10)²
=> S = 10u + u
=> S = 11u m
Constant speed 1.2u for 15 secs
S = 1.2u * 15
=> S = 18u m
Total Distance Covered d = 11u + 18u = 29u m
the given expression is :
2(4√16x) - 2(4√2y) + 34√81x - 4(4√32y)
⇒ 8(√16x) - 8(√2y) + 34√81x - 16√32y
⇒8×4√x - 8√2y + 34×9√x - 16√16×2y [∵ √16 = 4 and √81 = 9]
⇒32√x - 8√2y + 306√x - 16×4√2y
⇒(32√x + 306√x) - 8√2y - 16×4√2y
⇒338√x -72√2y
