The number of prime numbers lying between 384 and 391 is:

Appeared in: Bihar NHM CHO-2025

Explanation

A prime number is a whole number greater than 1 that has only two divisors: 1 and itself.
The numbers between 384 and 391 are 385, 386, 387, 388, 389, and 390.
By testing each number for divisibility, we find that only 389 is a prime number.
385 is divisible by 5; 386, 388, and 390 are divisible by 2; and 387 is divisible by 3.
Therefore, there is only 1 prime number in the specified range.

Option A: This is incorrect. There is only one prime number (389) in the range, not three.
Option C: This is incorrect. While there are multiple numbers in the range, only one of them (389) meets the definition of a prime number.
Option D: This is incorrect. This option likely represents a miscount of the numbers within the range or a misunderstanding of what a prime number is.

Visual 1: Infographic - A number line from 384 to 391, highlighting the number 389 and crossing out the non-prime numbers (385, 386, 387, 388, 390) with their respective divisors listed.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identifying prime numbers within a given range as background academic context rather than a clinical decision trigger.
This question assesses basic numeracy and logical reasoning, which are foundational skills for a nursing professional, particularly for tasks like medication dosage calculation and data interpretation.
While not a direct clinical scenario, strong mathematical skills prevent errors in clinical calculations, ensuring patient safety.
What if the range was 10 to 20? The prime numbers would be 11, 13, 17, and 19. The answer would then be 4.

How to Approach the Question

First, identify the range of numbers to be checked. The question asks for numbers 'between 384 and 391', which means the numbers 385, 386, 387, 388, 389, and 390.
Next, systematically evaluate each number in the range to see if it is prime.
Use divisibility rules to quickly eliminate non-prime (composite) numbers. For example, even numbers are divisible by 2, numbers ending in 5 are divisible by 5, and if the sum of digits is divisible by 3, the number is divisible by 3.
For any remaining numbers, test for divisibility by prime numbers (7, 11, 13, etc.) up to the square root of the number.
Count how many numbers from the list are prime to find the final answer.

Concept Tested & Keywords

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Practise the full Bihar NHM CHO-2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.