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Random + Random + Random #2 (Posted on 2025-03-07) Difficulty: 3 of 5
Let A, B and C each be random real numbers chosen from the uniform interval (0,1) and z=A+B+C.

If z is written in scientific notation, define X as the second digit of z.

Find the probability distribution of X.

No Solution Yet Submitted by K Sengupta    
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Some Thoughts Computer Solution | Comment 1 of 2
Simulation with 100,000,000 iterations:

[0.1143, 0.1138, 0.1122, 0.1097, 0.1062, 0.1017, 0.0962, 0.0898, 0.0823, 0.0738]

----
import random
data = [0 for i in range(10)]
reps = 100000000
for i in range(reps):
    a = random.random()
    b = random.random()
    c = random.random()
    sm = a+b+c
    st = str(sm)
    st = st.replace('.','')
    leading_zero = True
    while leading_zero:
        if st[0] == '0':
            st = st[1:]
        else:
            leading_zero = False
    z = int(st[1])
    data[z] += 1

histo = [d/sum(data) for d in data]
print(histo)

  Posted by Larry on 2025-03-07 09:06:58
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