Mrs. Woods wants to give each of her 25 students a pencil on the first day
1 answer:
You might be interested in
Step-by-step explanation:
The upstream speed is S / t₁, and the downstream speed is S / t₂.
If we say f is the speed of the fish in calm water, and r is the speed of the river, then:
f − r = S / t₁
f + r = S / t₂
If we say T is the time it takes to cross the river, then the speed perpendicular to the river is ℓ/T, the speed parallel to the river is r, and the overall speed is f.
Using Pythagorean theorem:
f² = (ℓ/T)² + r²
f² − r² = (ℓ/T)²
(f − r) (f + r) = (ℓ/T)²
(S / t₁) (S / t₂) = (ℓ/T)²
S² / (t₁ t₂) = (ℓ/T)²
(t₁ t₂) / S² = (T/ℓ)²
√(t₁ t₂) / S = T/ℓ
T = ℓ√(t₁ t₂) / S
Answer:
The speed of the cyclist is 10 miles per hour .
Step-by-step explanation:
Given as :
The distance cover by cyclist = = 20 miles
The distance cover by biker = = 6 miles
The speed of biker = = s mph
The speed of cyclist = = 7 + s mph
The time taken by both cyclist and biker = t hour
Now. Distance = Speed × Time
So, =
× t
Or, 20 = s × t
Or, t = .....1
And ,
=
× t
or, 6 = s t
Or, t = ....2
From Eq 1 and 2
I.e =
Or, 20 s = 6 ( 7 + s )
Or, 20 s - 6 s = 42
Or, 14 s = 42
∴ s =
I,e s = 3 miles per hour
So, The speed of biker = = s = 3 miles per hour
And The speed of cyclist = = 7 + s = 7 + 3= 10 miles per hour
Hence The speed of the cyclist is 10 miles per hour . Answer