Answer:
Let the speed of the train be x km/h.
Case 1:
Distance = 288 km
Speed = x km/h
Time = Distance/Speed
= 288/x h
Case 2:
Distance = 288 km
Speed = (x+4) km/h
Time = 288/x + 4 h
Since 288/x > 288/x + 4
288/x - 288/x+4 = 1
288[1/x - 1/x+4 ] = 1
[ x + 4 - x / x(x + 4) ] = 1/288
[4 / x^2 + 4x ] = 1/288
x^2 + 4x = 1152
x^2 + 4x - 1152 = 0
x^2 + 36x - 32x - 1152 = 0
x(x + 36) - 32(x + 36) = 0
(x + 36)(x - 32) = 0
x + 36 = 0 , x - 32 = 0
x = -36 , x = 32
x = -36 , rejected since speed cannot be negative.
Therefore , speed of the train = 32 km/h
This is a simple consequence of the Zero-sum problem: https://en.wikipedia.org/wiki/Zero-sum_problem
Answer:
8:39
Step-by-step explanation:
because when simplified, all the rest are 1:5
Area of Frame and Picture
Area = L * W
L = 9
W = 6
Area = 9*6 = 54 in²
Area of Picture
Area = L*W
L = 6
W = 4
Area = 6 * 4
Area = 24 in²
Area of Frame
Area of Frame = Total Area - Picture Area
Area of Frame = 54 - 24
Area of Frame = 30 in²
Answer:
B = 12
Step-by-step explanation:
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