instruction:
In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
question:
Problem: noelle walks from point a to point b at an average speed of 6 kilometers per hour . at what speed , in kilometers per hour , must noelle walk from point b to point a so that her average speed for the entire trip is 7 kilometers per hour ?
Options: a ) 6.75 , b ) 7 , c ) 7.25 , d ) 7.5 , e ) 8.4
answer:
e

question:
Problem: two trains of equal length , running with the speeds of 60 and 40 kmph , take 55 seconds to cross each other while they are running in the same direction . what time will they take to cross each other if they are running in opposite directions ?
Options: a ) 10 sec , b ) 16 sec , c ) 13 sec , d ) 67 sec , e ) 11 sec
answer:
e

question:
Problem: i remember during the school days , the teacher asked the class ' ' can you tell me the sum of the first 50 odd numbers ? ' ' . i ran quickly to the teacher and told her ' ' the answer is 2500 ' ' . the teacher replied ' ' lucky guess ' ' . she then asked me ' ' can you tell me the sum of first 75 odd numbers ? ' ' . i wait for approx 10 seconds and replied with the correct answer . how can i answer so quickly and whats the correct answer ?
Options: a ) 5624 , b ) 5625 , c ) 5626 , d ) 5627 , e ) none
answer:
b