It should be 25xy that is the correct answer i did this today
Answer:
there are 70 possible choices for the four locations to apply the new ointment
Step-by-step explanation:
Since we have a total of 8 locations ( 4 to the new ointment and 4 to the control) , each one can be chosen and since the order of the locations that are chosen for the new ointment is not relevant , then we know that the number of choices is given by the number of combinations of 4 elements in 8
number of combinations = 8 possible locations to the first ointment * 7 possible locations to the second ( since the first one was already located) * 6 to the third * 5 locations for the fourth / number of times the same combination is repeated ( the same locations but in different positions) = 8*7*6*5 / (4 possible positions for the first ointment* 3 possible positions to the second ointment (since the first one was already located * 2 possible positions of the third * 1 possible position of the fourth)
therefore
number of combinations = 8*7*6*5/(4*3*2*1 ) = 8!/((8-4)!*4!) = 70 possible combinations
thus there are 70 possible choices for the four locations to apply the new ointment
Maria do 1/2 work in 1 hour
Sasha do 1/3 work in 1 hour
Thus,
1/2+1/3=5/6 work in 1 hour
5/6 work in = 1 hour
1 work in =6/5=1.2 hours =72 minutes
The radius is half the diameter, so the formula would be r=d divided by 2
