Answers:
500meters
Explanation:
| Speed = | ![]() | 78 x | 5 | ![]() | m/sec | = | ![]() | 65 | ![]() | m/sec. |
| 18 | 3 |
Time = 1 minute = 60 seconds.
Let the length of the tunnel be x metres.
| Then, | ![]() | 800 + x | ![]() | = | 65 |
| 60 | 3 |
3(800 + x) = 3900
x = 500| Speed = | ![]() | 78 x | 5 | ![]() | m/sec | = | ![]() | 65 | ![]() | m/sec. |
| 18 | 3 |
| Then, | ![]() | 800 + x | ![]() | = | 65 |
| 60 | 3 |
3(800 + x) = 3900
x = 500