Maths question from Social Forest Worker exam, 2026 by JKSSB
A coin is tossed 5 times. Each head contributes +1 and each tail contributes-1. What is the probability that the total sum is exactly +1?
Last updated Jul 21, 2026
Correct Answer:
Option A —
5/16
Here is the step-by-step breakdown without using any math symbols:
Step 1: Find the total number of outcomes
Each time a coin is tossed, there are two possible outcomes: heads or tails.
For five tosses, the total number of possible sequences is calculated by doubling the possibilities for each additional toss: two, four, eight, sixteen, thirty-two.
Thus, there are 32 total possible outcomes.
Step 2: Determine the required heads and tails
Each head adds one point, and each tail subtracts one point.
To reach a final score of positive one across five tosses, you must get three heads and two tails.
Three heads contribute three points, and two tails take away two points, leaving a final score of positive one.
Step 3: Count the successful combinations
There are 10 different ways to land three heads and two tails in five tosses:
Head, Head, Head, Tail, Tail
Head, Head, Tail, Head, Tail
Head, Head, Tail, Tail, Head
Head, Tail, Head, Head, Tail
Head, Tail, Head, Tail, Head
Head, Tail, Tail, Head, Head
Tail, Head, Head, Head, Tail
Tail, Head, Head, Tail, Head
Tail, Head, Tail, Head, Head
Tail, Tail, Head, Head, Head
Step 4: Calculate the probability
There are 10 favorable outcomes out of 32 total possibilities, making the probability 10 out of 32.
Reducing this fraction by halving both numbers gives 5 out of 16.
Correct Answer:
A) 5/16
Answer verified by Quintessence Classes faculty — Karan Nagar, Srinagar.
