The ceiling function of a real number $x$, denoted by $\operatorname{ce}(x)$, is defined as the smallest integer that is greater than or equal to $x$. Similarly, the floor function, denoted by $f l(x)$, is defined as the largest integer that is smaller than or equal to $x$. Which one of the following statements is NOT correct for all possible values of $x$ ?

Find the odd one out in the set: {19, 37, 21, 17, 23, 29, 31, 11}

In the following series, identify the number that needs to be changed to form the Fibonacci series.

1, 1, 2, 3, 6, 8, 13, 21, …

The real variables $x, y, z$, and the real constants $p, q, r$ satisfy

$\frac{x}{pq - r^2} = \frac{y}{qr - p^2} = \frac{z}{rp - q^2}$

Given that the denominators are non-zero, the value of $px + qy + rz$ is