Asked by Machelle
The Sum Of The Digits On A Digital Clock Is 15. The Number Of Minutes Is 5 Times The Number Of Hours What Time Is It?
Answers
Answered by
Reiny
Case1: the number of hours is single digit
hours --- h
unit digit of minutes --x
tens digit of minutes --y
x+10y = 5h **
x+y+h = 15
h = 15-x-y
5h = 75 - 5x-5y ***
equating ** and ***
x+10y = 75-5x-5y
6x + 15y = 75
2x + 5y = 25
x = (25-5y)/2
--> 25 - 5y must be even so it divides evenly by 2,
values of 25-5y , 0 ≤ y≤ 5 :
25
20 <--- y = 1 , x = 10 , not possible
15
10 <--- y = 3 , x = 5 , h = 15-3-5 = 7
5
0
the time is 7:35
check:
6+3+5 = 15 , check
35 = 5(7), check
hours --- h
unit digit of minutes --x
tens digit of minutes --y
x+10y = 5h **
x+y+h = 15
h = 15-x-y
5h = 75 - 5x-5y ***
equating ** and ***
x+10y = 75-5x-5y
6x + 15y = 75
2x + 5y = 25
x = (25-5y)/2
--> 25 - 5y must be even so it divides evenly by 2,
values of 25-5y , 0 ≤ y≤ 5 :
25
20 <--- y = 1 , x = 10 , not possible
15
10 <--- y = 3 , x = 5 , h = 15-3-5 = 7
5
0
the time is 7:35
check:
6+3+5 = 15 , check
35 = 5(7), check
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.