Hope this isn't too confusing
All of the numbers have different shortcuts.
1. Yes. Divisible by 4: if last two digits are divisible by 4 then the whole number is yes)
2. No. Divisible by 6: it must be even and when you add them up, (44) it must be divisible by 3 (no, 44 is not divisible by 3)
3. Divisible by 8: ( last 3 numbers are divisible by 8 (312) = 39 ( yes it is)
4 Yes. Divisible by 11: ( sum of digits at odd places and sum of digits at even spaces,is either 0 or divisible by 11) yes, 278949. (2+8+9) + (7+9+9)= 19 + 25 = 44 and 44 is divisible by 11)
5. No. Divisible by 12 (divisible by 3 and 4, sum of digits is divisible by 3 ; and last 2 digits divisible by 4: 87654395 : 52/3= 18 (yes) 95/4(no) this number not divisible by 12
6. No. Divisible by 15: divisible by 3 and 5 ..87654385 = 46/3 = 15..(No) divisible by 5 yes. The number is not divisible by 15
The question also states that Lucy has a winning probability of 1/50, which means that she has 1 chance of winning if the total runners were 50. Therefore, there are 49 runners who may be faster than her.
The fact that Lucy is the 50th slowest runner, means that starting from the slowest she is in 50th position, therefore there are 49 runners that are slower than her.
The total number of runners will be the sum of those faster than Lucy, those slower than Lucy and Lucy:
49 + 49 + 1 = 99
There are 99 runners in Lucy's school.
Answer:
-5.5
Step-by-step explanation:
