Answer:
Input impedance of this transformer is 50 ohms.
Explanation:
Given that,
Number of turns in the primary coil, 
Number of turns in the secondary coil, 
Output impedance of the transformer, 
The number of turns and the impedance ratio in the step down transformer is given by :

So, the input impedance of this transformer is 50 ohms. Hence, this is the required solution.
False, the ice box was invented in the 1930's, the earliest for of food preservation was probably a shaded place, cave or smoking the food. the earliest forms of food preservation are hard to prove and I don't know what they are either I was just making and educated guess.