Suppose A , B , C , D , and E are distinct positive integers such that A < B < C < D < E , their median is 1 0 and their mean is 1 5 . Find the maximum possible value of D .
This problem is posed by Michael T.
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Good job writing the solution!
C is the median since it is the middle-most number. Therefore, C = 10.
Since mean = 15, (A + B + 10 + D + E)/5 = 15
Simplifying: A + B + D + E = 65
We want to maximise D, but E is greater than D. Hence, substitute E = D + 1 A + B + D + D + 1 = 65 A + B + 2D = 64
Use the smallest numbers possible for A and B (1 and 2 respectively). But, 1 and 2 = 3, which will give a fraction for an answer for D.
Hence, substitute 1 and 3 for A and B: 2D = 60 D = 30
Since C is the 3rd largest number out of the five, it is the median, so C = 1 0 . Also, from the value of the 5 numbers mean, we can calculate that A + B + C + D + E = 5 × 1 5 = 7 5 , and thus, A + B + D + E = 7 5 − 1 0 = 6 5 .
As we want to maximize D , the values of A , B and E should be minimized. Thus, A and B should take the smallest possible positive values, 1 and 2 (ie. A = 1 and B = 2 ). This leaves us with D + E = 6 5 − 1 − 2 = 6 2 . Noting the restriction that D < E , the largest value of D is therefore 3 0 .
Why A can not be equal to zero ?
It states that they are all distinct positive integers, so none of them can be zero.
mean = 15 median =10 let A<B<C<D<E by using formula .... median = digit/member =10/5 =2 mean = product * meAN =2*15=30
First of all the meanings. When taking about a median here it is the middle value in anything, if you don't know about median then look it up. The median was given as 10, there are 5 values A, B, C, D, E which are arranged in order therefore C is the median whose value is 10. Now the question asks for the MAXIMUM value of D. Therefore let A=1, B=2, C=10 (given) and the two left are D and E. The mean is 15. A+B+C+D+E=75 . D+E= 75-13 D+E=62 Now since D is less than E and we need the MAXIMUM value of D therefore divide 62 by 2 and you get 31. D=30 because D<E
For maximizing value of D , we need to give least possible values to A & B, i.e., 1 and 2.
And , it is given that median (C) = 10.
Now,
1 + 2 + 10 + D + E = 5 * 15
D + E = 62
Maximum value which can be the value of D is 30 only because we are having a constraint D < E (i.e., 32), E can't be even 31 that will make D = E.
So, D = 30 (Ans)
For D to be maximum, we must find the smallest value for A and B. Not for C, because the median is 10, so the value of C has been determined.
The smallest positive integer is 1, hence A = 1
A < B , do the smallest possible B is 1 + 1 , B = 2
C is the median so, C = 1 0
Now, the mean is 5 and there are 5 numbers, the sum is 5 ∗ 1 5 = 7 5 7 5 = A + B + C + D + E
By the known variable above, we get D + E = 6 2
D < E so,the maximum value of D D = 2 6 2 − 1 = 3 0
Firstly we need to find the lowest positive integer of A which is 1.
Secondly, we know that we are trying to find the maximum number for D therefore B must be the next smallest positive integer which is 2.
Thirdly we know C is 10 since it states that the median is 10
Finally finding D and E: Since the mean is 15, that means the sum of all letters (A to E) divided by 5 must equal to 15
(1+2+10+D+E) divided by 5 = 15
Times 5 on both sides we get: 13+D+E = 75
Then take away 13 from both sides we get: D + E = 62
Therefore D = 30 since D must be smaller than E.
+ +10+ _ _ _ _ _ _ _ _ _ _ _ = 15 5 i just think of a less two consecutive numbers to be filled in the first and second blank such as 1 and 2 so that the the number on the fourth and fifth blank will higher .. think of a number when u add to 13 the sum is 75 because 75 divided 5 is 15 .... the answer is 62 ...again think 0f a two number whose sum is 62 . the answer is 30 and 32
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We know that if we arrange n numbers in increasing order then their median would be ( 2 n ) t h term if n is odd.
Given that A < B < C < D < E , C would be their median, so C = 1 0
Now, 5 A + B + C + D + E = 1 5 ⇒ A + B + C + D + E = 7 5 ⇒ A + B + D + E = 6 5
To maximize D , we need to minimize A , B , E . Since they're are distinct positive integers, we let A = 1 , B = 2 . So, we are left with D + E = 6 2 . Since D < E ⇒ D < 2 6 2 = 3 1
Hence, maximum value of D = 3 0