John has 3 unique coins such that the probability of obtaining a head when the coin is flipped is 1/10, 2/10 and 3/10, respectively. If he flips each of the 3 coins once, the probability that at least 1 heads appears is p. What is the value of 1000p?

To find the probability that at least one head appears when flipping the three coins, we can calculate the probability that no heads appear and then subtract it from 1.

The probability of obtaining a tail when flipping a coin is 1 minus the probability of obtaining a head. Therefore, the probability of obtaining a tail for each of the three coins is:

Coin 1: 1 - 1/10 = 9/10
Coin 2: 1 - 2/10 = 8/10
Coin 3: 1 - 3/10 = 7/10

Since the three coins are independent events, we can multiply these probabilities together to find the probability of no heads appearing:

P(no heads) = (9/10) * (8/10) * (7/10)

Next, we can subtract the probability of no heads from 1 to find the probability of at least one head appearing:

P(at least one head) = 1 - P(no heads)

Now we can calculate this probability:

P(at least one head) = 1 - (9/10) * (8/10) * (7/10)
= 1 - (9 * 8 * 7) / (10 * 10 * 10)
= 1 - 504 / 1000
= 496 / 1000

Finally, to find the value of 1000p, we multiply the probability by 1000:

1000p = 1000 * (496 / 1000)
= 496