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Question

Answers

A. \[100\]

B. \[50\]

C. \[95\]

D. \[93\]

Answer
Verified

As per the given data, we have to find the between \[1\] and \[200\] that are multiples of \[5\] and should also be divisible by \[3\]

The number that is multiple of \[5\] between \[1\] and \[200\] is \[5,10,15...200\] and number divisible by \[3\] are \[3,6,9...198\]

The number satisfying both the conditions are \[15,30,...195\]

In the above-obtained series, we can observe that the first term is \[15\] and the difference is also \[15\] while the last term is \[195\].

Now, substituting the values in the formula of A.P, i.e.

\[{{\text{T}}_{\text{n}}}{\text{ = a + (n - 1)d}}\] we get,

\[

{\text{195 = 15 + }}\left( {{\text{n - 1}}} \right){\text{15}} \\

\Rightarrow {\text{180 = (n - 1)15}} \\

\]

Simplifying it further and calculating the value of n, we get,

\[ \Rightarrow \dfrac{{180}}{{15}}{\text{ = n - 1}}\]

On simplifying further we get,

\[ \Rightarrow {\text{12 = n - 1}}\]

On rearranging we get,

\[ \Rightarrow {\text{12 + 1 = n}}\]

Hence , \[{\text{n = 13}}\]

Hence , In the above obtained series we can observe that first term is \[{\text{5}}\] and difference is also \[{\text{5}}\] while the last term is \[195\]

Now, substituting the values in the formula of A.P, i.e.

\[{{\text{T}}_{\text{n}}}{\text{ = a + (n - 1)d}}\] we get,

\[

\Rightarrow {\text{195 = 5 + }}\left( {{\text{n - 1}}} \right){\text{5}} \\

\Rightarrow {\text{190 = (n - 1)5}} \\

\]

On calculating the value of n we get,

\[ \Rightarrow \dfrac{{190}}{5}{\text{ = n - 1}}\]

On simplifying we get,

\[ \Rightarrow {\text{38 = n - 1}}\]

\[ \Rightarrow {\text{ n = 39}}\]

Now, calculating the total number of terms that are divisible by \[3\].

Hence, In the above-obtained series we can observe that first term is \[{\text{3}}\] and difference is also \[{\text{3}}\] while the last term is \[198\]

Now, substituting the values in the formula of A.P, i.e.

\[{{\text{T}}_{\text{n}}}{\text{ = a + (n - 1)d}}\] we get,

\[

\Rightarrow {\text{198 = 3 + }}\left( {{\text{n - 1}}} \right)3 \\

\Rightarrow {\text{195 = (n - 1)3}} \\

\]

Hence calculating the value of n,

\[ \Rightarrow \dfrac{{195}}{3}{\text{ = n - 1}}\]

On further simplification we get,

\[ \Rightarrow {\text{66 = n - 1}}\]

\[ \Rightarrow {\text{n = 67}}\]

Hence , we need to add all the terms satisfying the condition of divisible by \[3\] and multiples of \[5\] and subtract the terms common in both of them

So, it will be

\[{\text{67 + 39 - 13 = 93}}\]

Hence,