A tank is full of  $500$L of water. How much water will be filled in $45$tanks? If $25$buckets can be filled with one tank of water, how many buckets in all can be filled with the water in $45$tanks?

Given:

Capacity of a tank = $500$L

No. of buckets that can be filled with $1$tank = $25$

To find:

Quantity of water that can be filled in $45$tanks.

No. of buckets that can be filled with $45$tanks.

Solution:

Capacity of a tank = $500$L

Capacity of $45$tanks =?

By using the cross multiplication method,

Capacity of $45$tanks = $500\times 45$

Solving  the multiplication,

$500\times 45=500\times (40+5)$

$\Rightarrow 500\times 45=(500\times 40)+(500\times 5)$ 

$\Rightarrow 500\times 45=20000+2500$

                      = $22500$

Therefore, $22500$L of water can be filled in $45$tanks.

No. of buckets that can be filled with $1$tank = $25$

No. of buckets that can be filled with $45$tanks =?

By using the cross multiplication method,

No. of buckets that can be filled with $45$tanks =$45\times 25$

                                                                      = $1125$

Therefore, $1125$buckets can be filled with $45$tanks.

Hence, the correct option is A.