a car journey in 10 hours the first half at 21 kilometre per hour and the rest at 24 kilometre per hour the distance travelled by the car is
Answers
Step-by-step explanation:
Hi there!
Here's the answer:
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Distance = Speed × Time
METHOD - 1 :
Total Journey made = 10 Hrs
Let total distance be d Km
First half of the distance /frac{d}{2}/fracd2 travelled at 21 kmph in x hrs
=> d/2 = 21xd/2=21x
=> d = 42xd=42x --------(1)
Second Half of the distance (d/2) travelled at 24 kmph in (10-x) Hrs
=> \frac{d}{2} = 24 × (10 - x)
2
d
=24×(10−x)
=> d = 48(10 - x)d=48(10−x)
=> x = 10 - (\frac{d}{42})x=10−(
42
d
) -------(2)
From eq(1) & eq(2)
=> \frac{d}{42} = 10 - (\frac{d}{48})
42
d
=10−(
48
d
)
=> \frac{d}{42} + \frac{d}{48} = 10
42
d
+
48
d
=10
=> d = \frac{2×5×2×3×7×8}{3×5}d=
3×5
2×5×2×3×7×8
=> d = 224 Kmsd=224Kms
•°• Required distance covered = 224 km
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Method -2 : Using Formula
¶¶¶ Suppose a man covers a certain distance at x kmph and an equal distance at y kmph.
Then,
The average speed during the whole journey is \frac{2xy}{x+y} kmph
x+y
2xy
kmph
Given, x = 21 y = 24
Average speed = \frac{2×21×24}{21+24}
21+24
2×21×24
Distance = speed × time = 22.4 × 10 = 224 km
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Hope it helps
Answer:
speed=distance/time
time=distance/speed
total time taken car 10hour and first half and rest distance
10=d/2×21+d/2×24
10=d/42+d/48
10=15d/336
d=3360/15
d=224 km