I would answer, but I don’t see the graph. If you add the graph I could help (if you want of course, not trying to be rude. Sorry!)
P(at least 5 rolls until 1) = P(4 rolls are not 1) = 5/6 x 5/6 x 5/6 x 5/6 = 0.4823 (4sf)
Fewer than 7 rolls to get second 1 after first takes 3 rolls means second occurs on 4th, 5th or 6th roll
The probability of each of these is 1/6, 5/6 x 1/6 and 5/6 x 5/6 x 1/6 respectively.
P(second 1 on 4th, 5th or 6th roll) = 1/6 + 5/36 + 25/216 = 91/216 = 0.4213 (4sf)
Answer:
the answer is C
Step-by-step explanation:

Answer:
a(n) = 20*2.5^(n - 1)
Step-by-step explanation:
Note that 50 is 2.5 times 20, and that 125 is 2.5 times 50. Thus the common factor is 2.5. The formula for the nth term is
a(n) = a(1)*r^(n - 1) => a(n) = 20*2.5^(n - 1)