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A number is selected at random from the first twenty-five natural numbers. If it is a composite number, then it is divided by `5`. But if it is not a composite number, it is divided by `2`. The probability that there will be no remainder in the division is

A

`(11)/(30)`

B

`0.4`

C

`0.2`

D

none of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will follow these steps: ### Step 1: Identify the Sample Space The sample space consists of the first 25 natural numbers, which are: \[ S = \{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25\} \] ### Step 2: Identify Composite Numbers Composite numbers are numbers that have more than two factors. The composite numbers from 1 to 25 are: \[ \{4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25\} \] This gives us a total of 15 composite numbers. ### Step 3: Identify Non-Composite Numbers Non-composite numbers include prime numbers and the number 1. The non-composite numbers from 1 to 25 are: \[ \{1, 2, 3, 5, 7, 11, 13, 17, 19, 23\} \] This gives us a total of 10 non-composite numbers. ### Step 4: Determine Divisibility Conditions - If a composite number is selected, it is divided by 5. - If a non-composite number is selected, it is divided by 2. ### Step 5: Find Composite Numbers Divisible by 5 The composite numbers from our list that are divisible by 5 are: \[ \{10, 15, 20, 25\} \] This gives us a total of 4 favorable outcomes from composite numbers. ### Step 6: Find Non-Composite Numbers Divisible by 2 The only non-composite number from our list that is divisible by 2 is: \[ \{2\} \] This gives us a total of 1 favorable outcome from non-composite numbers. ### Step 7: Calculate Total Favorable Outcomes The total number of favorable outcomes (no remainder in division) is: \[ 4 \text{ (from composites)} + 1 \text{ (from non-composites)} = 5 \] ### Step 8: Calculate Total Outcomes The total number of outcomes in the sample space is: \[ 25 \] ### Step 9: Calculate Probability The probability of selecting a number such that there is no remainder in the division is given by: \[ P(\text{no remainder}) = \frac{\text{Number of favorable outcomes}}{\text{Total outcomes}} = \frac{5}{25} = \frac{1}{5} \] ### Final Answer Thus, the probability that there will be no remainder in the division is: \[ \frac{1}{5} \text{ or } 0.2 \] ---

To solve the problem, we will follow these steps: ### Step 1: Identify the Sample Space The sample space consists of the first 25 natural numbers, which are: \[ S = \{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25\} \] ### Step 2: Identify Composite Numbers Composite numbers are numbers that have more than two factors. The composite numbers from 1 to 25 are: ...
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