Answer:
2 km/h
Step-by-step explanation:
Let x represent the speed of the river current, t₁ be the time spent rowing against the current and t₂ be the time spent rowing with the current.
Since the speed of the still water = 20 km/h.
The speed of rowing against the current = (20 - x)
The speed of rowing with the current = (20 + x)
We know that velocity = distance / time. Hence time = distance / velocity
t₁ = 36 / (20 - x)
t₂ = 22 / (20 + x)
but t₁ + t₂ = 3 hours
Therefore:
3 = 36 / (20 - x) + 22 / (20 + x)
multiply through by 400 - x²
3(400 - x²) = 36(20 + x) + 22(20 - x)
1200 - 3x² = 720 + 36x + 440 - 22x
3x² + 14x -40 = 0
This gives x = -6.7 or x = 2
x cannot be negative therefore x = 2 km/h
The speed of the river current is 2 km/h
Answer: p = 0.73
Step-by-step explanation:
Given that,
73% of the audience was under 20 years old :
so, probability (p) = 0.73
n = 146
Mean of the distribution of sample proportion = ?
According to central limit theorem,
np(1-p) ≥ 10
146 × 0.73(0.27) ≥ 10
28.77 ≥ 10
∴ Central limit theorem assumes that the sample distribution of the sample proportion is normally distributed.
Hence, the mean of the distribution of sample proportion:
μ = p = 0.73
Answer: yes
Step-by-step explanation:
The product of side length and altitude is area. The area remains the same regardless of how you measure it.
From the first side and altitude,
.. area = side*altitude = (4.2 cm)*(3.6 cm) = 15.12 cm^2
From the second side and altitude
.. area = side*altitude
.. 15.12 cm^2 = side*(2.4 cm)
.. side = (15.12 cm^2)/(2.4 cm) = 6.3 cm
The perimeter is the sum of the measures of all sides. Opposite sides are of equal measure.
.. perimeter = 2*(4.2 cm +6.3 cm) = 21.0 cm