Step 1: Write the formulas for mean and variance of Binomial distribution.
For a Binomial distribution \(B(n,p)\),
\[
\text{Mean}=np
\]
and
\[
\text{Variance}=npq
\]
where
\[
q=1-p
\]
Step 2: Use the given mean.
It is given that the mean is \(15\).
Therefore,
\[
np=15
\]
Step 3: Use the given variance.
It is given that the variance is \(10\).
So,
\[
npq=10
\]
Using \(np=15\), we get
\[
15q=10
\]
\[
q=\frac{10}{15}
\]
\[
q=\frac{2}{3}
\]
Step 4: Find the value of \(p\).
Since,
\[
p+q=1
\]
we have
\[
p=1-\frac{2}{3}
\]
\[
p=\frac{1}{3}
\]
Step 5: Find the value of \(n\).
Using
\[
np=15
\]
Substitute \(p=\dfrac{1}{3}\),
\[
n\left(\frac{1}{3}\right)=15
\]
\[
n=15\times 3
\]
\[
n=45
\]
Step 6: Final conclusion.
Hence, the value of the parameter \(n\) is
\[
\boxed{45}
\]