Solving a Binomial Probability Problem: Exactly 2 Successes in 4 Rolls with p = 1/6

If you’ve ever tossed a die and asked, “What’s the chance of rolling a 4 exactly twice in only 4 rolls?” — you’re dealing with a classic binomial probability problem. In this article, we break down how to solve this using the binomial distribution formula, with $ n = 4 $, success probability $ p = rac{1}{6} $, and exactly $ k = 2 $ successes.


Understanding the Context

What is a Binomial Probability Problem?

A binomial probability problem describes experiments consisting of $ n $ independent trials, each with two possible outcomes: success or failure. The probability of success $ p $ remains constant across trials, and we want to compute the probability of exactly $ k $ successes.

The binomial probability formula is:

$$
P(X = k) = inom{n}{k} p^k (1 - p)^{n - k}
$$

Key Insights

Where:
- $ inom{n}{k} $: the binomial coefficient, representing the number of ways to choose $ k $ successes from $ n $ trials
- $ p $: probability of success on a single trial
- $ 1 - p $: probability of failure


Problem Setup

Given:
- Number of trials $ n = 4 $
- Success probability $ p = rac{1}{6} $ (rolling a 4 with a fair die)
- Number of desired successes $ k = 2 $

We want to find:
The probability of rolling exactly two 4s in four rolls of a fair die.

🔗 Related Articles You Might Like:

📰 You’ll Never Turn Back! The Ultimate Gruyere Cheese Substitute That Tastes Like Luxury! 📰 This Gruyere Cheese Substitute Mimics Every Flavor—Sneaky, Delicious, and Ready to Shock! 📰 Granny Said You’d Never Find a Better Gruyere Cheese Substitute—Here’s the Secret! 📰 Total Xbox Server Outage Is Your Game Lagging Or Just Lagging 📰 Town Of Cacagos Bordered By Chiwullu Chiwokuch Icc Ndenye Mende Icc Ntenquiru Icc And Bui Semi Technical College To The Southeast 📰 Track Your Dog All Daythis Hidden Gps Animal Bracelet Is A Life Saver 📰 Tradition Meets Talent Asian Kids Inspiring Rise Lights Up The World Dont Miss This 📰 Transform Every Outfit With This Eye Catching Arm Cuffheres Why 📰 Transform Your Android Home Screen With These Shock Proven App Arrangement Tips 📰 Transform Your Arm With A Spiritual Angel Wing Tattooheres The Haunting Perfection 📰 Transform Your Art Gallery 10 Easy Watercolor Painting Ideas Youll Love 📰 Transform Your Art Game Ultimate Collection Of Anime Girl Coloring Pages You Wont Believe 📰 Transform Your Creativitydiscover The Ultimate Art Base Power 📰 Transform Your Favorite Scenes With Animeto The Ultimate Animation Magic Now Available 📰 Transform Your Fish Tank Into A Living Artwork Plants Rocks Youll Never Forget 📰 Transform Your Free Time With These Legal Anime Coloring Pagesperfect For All Ages 📰 Transform Your Gaming In Minutesthese Asus Monitors Are Revolutionizing Screens 📰 Transform Your Health Unlock The Mystery Of The Ampulla Hepatopancreatica Today

Final Thoughts


Step-by-Step Solution

Step 1: Identify parameters
- $ n = 4 $ (four rolls)
- $ p = rac{1}{6} $ (rolling a 4)
- $ k = 2 $ (exactly two 4s)
- Thus, $ 1 - p = rac{5}{6} $ (probability of not rolling a 4)

Step 2: Compute the binomial coefficient
The number of ways to choose 2 successes (rolling a 4) from 4 trials is:

$$
inom{4}{2} = rac{4!}{2!(4-2)!} = rac{24}{2 \cdot 2} = 6
$$

Step 3: Apply the binomial formula

$$
P(X = 2) = inom{4}{2} \left( rac{1}{6} ight)^2 \left( rac{5}{6} ight)^{4 - 2}
$$

$$
P(X = 2) = 6 \cdot \left( rac{1}{6} ight)^2 \cdot \left( rac{5}{6} ight)^2
$$

$$
P(X = 2) = 6 \cdot rac{1}{36} \cdot rac{25}{36} = rac{6 \cdot 25}{36 \cdot 36} = rac{150}{1296}
$$

Step 4: Simplify the fraction