UP Police Constable Exam Model Paper 3

The given series: Z1, Y4, X9, ______
The first element of each term is a letter that is in the reverse alphabetical order.
 

Z

$\stackrel{-1}{}$────▶

Y

$\stackrel{-1}{}$────▶

X

$\stackrel{-1}{}$────▶

W

Thus, the next term will start with 'W'.
The second element of each term is a number which is a square of natural numbers starting from 1.
$1^2=1;2^2=4;3^2=9;4^2=16$
Hence, the next term will be W16.