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If you multiply all the prime numbers from 1 to 80 and divide the result by 4, what do you get?

a) 32.5
b) 78.5
c) 189.5
d) 476.5

User Aroon
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1 Answer

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Final answer:

After multiplying all prime numbers from 1 to 80, you get an even number because it includes the prime number 2. Dividing this product by 4 must yield a whole number. Thus, the correct answer must be the only whole number provided, which is option d) 476.5.

Step-by-step explanation:

The question is asking to find the result of multiplying all prime numbers from 1 to 80 and dividing that product by 4. Remember that 1 is not a prime number, so we start with 2. The prime numbers from 1 to 80 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, and 79. When we multiple these together, the result is a very large number, which isn't necessary to compute because we can perform our analysis without finding the actual product.

Notice that among these primes, 2 is the only even prime number, and when we multiply all the primes together, the number 2 will be included, making the entire product even. Therefore, upon dividing by 4, which is essentially halving the number twice, we will still get a whole number since the original product contains a factor of 4 (from 2 x 2). So the results from options a), b), and c) can be eliminated because they are not whole numbers.

The correct option must be d) because it's the only whole number provided. Therefore, the answer to the student's question is d) 476.5, which is a whole number when divided by 4. We didn't need to actually multiply all the prime numbers together; just a quick logic check will do.

User Figbeam
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