Answer:
Probability, P(getting 2 toppings)= 0.1984
Step-by-step explanation:
Probability, P(1 toppings)= 1/7
Probability P of getting a particular topping is q = 1 - P = 1 - 1/7 = 6/7
Probability of( getting 2 toppings)= 7!/(2!5!)(1/7)^2 × (6/7)^5
P(getting 2 toopings)= (5040/240) × (0.020)× (0.4627)
P(getting 2 toppings)= 21 × 0.00948 = 0.1984
If you take the square root of 3, you get ~1.732, which is between 1.7 and 1.8
Find the rate in which both balls make one full rotation around the track.
Ball A:

It takes 30 seconds for Ball A to make a full rotation.
Ball B:

It takes 20 seconds for Ball B to make a full rotation.
Find the least common multiple of 20 and 30 to find the time at which they'll meet.
Multiples of 20: {20,40,60}
Multiples of 30: {30,60}
60 is the least common multiple of both 20 and 30.
The balls will meet again at
60 seconds.