Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 7)
7.
A man complete a journey in 10 hours. He travels first half of the journey at the rate of 21 km/hr and second half at the rate of 24 km/hr. Find the total journey in km.
Answer: Option
Explanation:
| (1/2)x | + | (1/2)x | = 10 |
| 21 | 24 |
 |
x | + | x | = 20 |
| 21 | 24 |
15x = 168 x 20
| x = |
 |
168 x 20 |  |
= 224 km. |
| 15 |
Discussion:
143 comments Page 7 of 15.
Abhinav said:
1 decade ago
The best way to choose the answer.
Check the option and find the multiple of 21 (divisible by 7) and.
(b) is right because it's a divisble by 7 and also multiple of 21.
Check the option and find the multiple of 21 (divisible by 7) and.
(b) is right because it's a divisble by 7 and also multiple of 21.
Jinto said:
1 decade ago
@suchitha
First calculate average speed of 21 and 24 using the formula 2xy/x+y then multiply it with 10 then we will get the answer distance = speed*time easy method.
First calculate average speed of 21 and 24 using the formula 2xy/x+y then multiply it with 10 then we will get the answer distance = speed*time easy method.
Niraj said:
6 years ago
(1/2)x 21 + (1/2)x 24 = 10.
x /21 + x /24 = 10 x 2.
8x /21x8 + 7x /24x7 = 20.
8x /21x8 + 7x /24x7 = 20.
15x = 20x168.
x = 20x168/15.
x = 3360/15.
x = 224km.
x /21 + x /24 = 10 x 2.
8x /21x8 + 7x /24x7 = 20.
8x /21x8 + 7x /24x7 = 20.
15x = 20x168.
x = 20x168/15.
x = 3360/15.
x = 224km.
Himanshu said:
12 months ago
Let the Distance = 2x.
So, By Formula T = D/S.
The distance covered by each = x.
10 = x/21+x/24,
5040 = 45x,
X = 122.
So Distance =2x,
= 2x122,
=224 Km.
So, By Formula T = D/S.
The distance covered by each = x.
10 = x/21+x/24,
5040 = 45x,
X = 122.
So Distance =2x,
= 2x122,
=224 Km.
(21)
Rose said:
6 years ago
The average speed is 2*21*24/45 which is 336/15 km/hr.
Speed=distance/time
So 336/15 = distance/10.
Therefore, distance = 336 * 10/15 which is 224 km.
Speed=distance/time
So 336/15 = distance/10.
Therefore, distance = 336 * 10/15 which is 224 km.
Niraj said:
6 years ago
@Niraj :STEP 1:- there will come divide(/) at the pace of multiple (x) I did mistake here so it will come in,
Step 1: x(1/2) /21 + x(1/2)/ 24 = 10.
Step 1: x(1/2) /21 + x(1/2)/ 24 = 10.
Gowthaman said:
1 year ago
Let's take a formula = 2XY/X + Y.
Here, X=21 and Y= 24.
So, the formula is = 2 * 21 * 24/21 + 24,
= 1008/45.
Here, your Answer = 22.4 * 10 = 224.
Here, X=21 and Y= 24.
So, the formula is = 2 * 21 * 24/21 + 24,
= 1008/45.
Here, your Answer = 22.4 * 10 = 224.
(32)
Ansh Raghav said:
11 months ago
@ALL.
According to the given question;
x/21 + x/24 =10
15x/168 = 10.
By cross multiplication;
168 × 10 = 15x.
1680 = 15x.
122 = x.
2x = 224.
According to the given question;
x/21 + x/24 =10
15x/168 = 10.
By cross multiplication;
168 × 10 = 15x.
1680 = 15x.
122 = x.
2x = 224.
(24)
Chakri said:
9 years ago
It is the first half of the distance. i.e x/2 not half of the time i.e 5 hours. So we cannot take 5 hours and multiply it with 21 and 24.
Somesh said:
9 years ago
Total journey:: 10hr.
1st half journey by 21km/hr = 21 * 5 = 105km.
2nd half journey by 24km/hr = 24 * 5 = 120 km.
So, 105+120 = 225km.
1st half journey by 21km/hr = 21 * 5 = 105km.
2nd half journey by 24km/hr = 24 * 5 = 120 km.
So, 105+120 = 225km.
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