If my calculations are correct I think it's 50
Since there is no repetition allowed, there are 10 possibilities for the 1st digit, 9 for the 2nd, 8 for the 3rd, and 7 for the 4th. This gives a total of (10)(9)(8)(7) = 5040 four-digit codes.
For all odd digits to be used, there are 5 possibilities for the 1st digit (1,3,5,7,9), 4 for the 2nd, 3 for the 3rd, 2 for the 4th. This gives a total of (5)(4)(3)(2) = 120 codes that only use odd digits.
Therefore there are 5040 - 120 = 4920 codes that do not consist of all odd digits. The probability is 4920/5040 = 41/42.
Answer:
10 km/h
Step-by-step explanation:
I'm not really sure about this but no ones answering your question and I wanna help.
So basically to calculate the average speed you need to divide the distance travelled by time taken
But you do not have the distance traveled. But it is mentioned that it takes u 30 minutes to walk from home to school when walking at 5 km/h so to find the distance all you have to do is... 30 x 5 = 150 km
Now that we have the time and distance all we have to do is find the average speed.
Average Speed = distance ÷ time
So 150 ÷ 15 = 10 km/h
B is the right answer for this
