Question

Some car radio models are protected by a security code. To activate the audio system, you must enter the secret code consisting of four digits. In the first case of a typing error, the person must wait 60 seconds to enter the code again. The wait time doubles compared to the previous wait time for each wrong entry. One person managed to activate the radio only on the fourth attempt, with 30 seconds being the time spent typing the secret code at each attempt. In cases of incorrect typing, she started the retry immediately after releasing the hold system.The total time, in seconds, spent by this person to activate the radio was equal toA) 300.B) 420.C) 540.D) 660.E) 1 020.

Answer 1

"In the first case of a typing error, the person must wait 60seconds to enter the code again.The wait time doubles compared to the previous wait time for each wrong entry."

The statement above implies that the Try/wait time for the code is 30 seconds.

The code was activated on the fourth attempt by a person.

The information provided above can be represented in the table below:

Total Try time is 120seconds and the Total Wrong time is 420seconds.

Hence, the total it took the person to activate the radio is 120 + 420 = 540seconds which is option C