Question
A train crosses a bridge in 15 secs while it crosses a
man standing on a platform in 8 secs. If the speed of train 108 km/hrs, then what will be the time taken by the train to cross a tunnel whose length is 210 meters more than the length of the bridge .Solution
ATQ, we can say that Speed of train is = (108 x 5)/18 = 30 m/s then, the Length of bridge is = 30 x 7 = 210 m {The "30 × 7" step comes from: Extra time over bridge = 15 − 8 = 7 sec = Bridge length = 30×7 = 210 m} then, the Length of tunnel = 210 + 210 = 420 m Length of train 108 × 5/18 = (x + 210)/15 30 × 15 = x + 210 x = 240 meter therefore, the Required time = (240 + 420)/30 = 22 seconds
1.2Â Â Â Â Â Â Â 4.2Â Â Â Â Â Â Â Â ? Â Â Â Â Â Â Â Â Â Â Â 18.2Â Â Â Â Â Â Â 33.2 Â Â Â Â Â Â 56.2
...5, 14, 41, 122, 365, 1094, ?
If 2.5 3.5 x 30 124 625
Then, x ² - 1 - 2x = ?
...157, 159, 189, 319, ‘?’, 1 407 , 2749 Â
1335Â Â Â Â Â Â 737Â Â Â Â Â Â Â Â 355Â Â Â Â Â Â Â Â 141Â Â Â Â Â Â Â Â 47Â Â Â Â Â Â Â Â Â Â ?
...8, 9, 15, ?,82.5, 250.50
22 44 176 1078 8448
...3 15 35 63 99 ?
95    216    72    241    ?    270
If   314     306      x      269       394    178    1480
Then, 1/3 x + 2x - x = ?
...
Relevant for Exams:
