All of the multiples of 3 on the hundred chart are shaded.

Which of the following describes the numbers shaded on the hundred chart?

\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|}
\hline
1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10 \\
\hline
11 & 12 & 13 & 14 & 15 & 16 & 17 & 18 & 19 & 20 \\
\hline
21 & 22 & 23 & 24 & 25 & 26 & 27 & 28 & 29 & 30 \\
\hline
31 & 32 & 33 & 34 & 35 & 36 & 37 & 38 & 39 & 40 \\
\hline
41 & 42 & 43 & 44 & 45 & 46 & 47 & 48 & 49 & 50 \\
\hline
51 & 52 & 53 & 54 & 55 & 56 & 57 & 58 & 59 & 60 \\
\hline
61 & 62 & 63 & 64 & 65 & 66 & 67 & 68 & 69 & 70 \\
\hline
71 & 72 & 73 & 74 & 75 & 76 & 77 & 78 & 79 & 80 \\
\hline
81 & 82 & 83 & 84 & 85 & 86 & 87 & 88 & 89 & 90 \\
\hline
91 & 92 & 93 & 94 & 95 & 96 & 97 & 98 & 99 & 100 \\
\hline
\end{tabular}

Choose one answer:

A. The shaded numbers are all prime.
B. The shaded numbers are all composite.
C. Some shaded numbers are prime and some are composite.



Answer :

To solve the problem of determining the nature of the shaded numbers (multiples of 3) within the hundred chart, let's follow these steps.

1. Identify the multiples of 3 from 1 to 100:
- Multiples of 3 are numbers that can be expressed as [tex]\( \text{n} \times 3 \)[/tex] where [tex]\( \text{n} \)[/tex] is an integer.
- From 3 to 99, we list the multiples: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99.

2. Determine which of these multiples are prime numbers:
- Prime numbers are numbers greater than 1 that have no divisors other than 1 and themselves.
- Among the multiples of 3 listed above, the only prime number is 3. This is because all other multiples of 3 are not prime; they have at least 3 as a factor in addition to 1 and themselves.

3. Identify the composite numbers:
- Composite numbers are numbers greater than 1 that have more than two positive divisors.
- Therefore, all other multiples of 3 except 3 itself are composite numbers.

So, based on the analysis:

- The multiples of 3 in the range from 1 to 100 are: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99.
- Among these, the number 3 is prime.
- All other multiples are composite.

Therefore, the correct answer is:

(c) Some shaded numbers are prime and some are composite.