The echo will be distinctly heard only at ordinary temperature if the distance of the reflecting surfaces from the source of sound is atleast;
1.
1120 feet
2.
120 feet
3.
56 feet
4.
100 feet
The correct answer is (3)
Warning: include(../bars/sidebar.php): failed to open stream: No such file or directory in /home/shopingc/theinfobia.com/question.php on line 74
Warning: include(): Failed opening '../bars/sidebar.php' for inclusion (include_path='.:/opt/alt/php74/usr/share/pear') in /home/shopingc/theinfobia.com/question.php on line 74
Warning: include(../inc/footer.php): failed to open stream: No such file or directory in /home/shopingc/theinfobia.com/question.php on line 79
Warning: include(): Failed opening '../inc/footer.php' for inclusion (include_path='.:/opt/alt/php74/usr/share/pear') in /home/shopingc/theinfobia.com/question.php on line 79