the average of 5 numbers is 30 & 4 numbers is 25 find the 5th number. plzz help
2007-04-04 17:56:15 · 19 answers · asked by saira s 1 in Science & Mathematics ➔ Mathematics
50
2007-04-04 17:59:00 · answer #1 · answered by Chris32 2 · 0⤊ 0⤋
The average of 5 numbers is 30, so:
(a + b + c + d + e)/5 = 30
and
a + b + c + d + e = 150 (multpliy both sides by 5)
So we know the five numbers add up to 150..
The average of 4 numbers is 25, so:
(a + b + c + d)/4 = 25
and
a + b + c + d = 100 (multiply both sides by 4)
So we know 4 numbers add up to 100.
150 - 100 = 50.
The fifth number is 50
2007-04-06 00:23:07 · answer #2 · answered by Kinu Sharma 2 · 0⤊ 0⤋
The average of 5 numbers is 30, so:
(a + b + c + d + e)/5 = 30
and
a + b + c + d + e = 150 (multpliy both sides by 5)
So we know the five numbers add up to 150..
The average of 4 numbers is 25, so:
(a + b + c + d)/4 = 25
and
a + b + c + d = 100 (multiply both sides by 4)
So we know 4 numbers add up to 100.
150 - 100 = 50.
The fifth number is 50
2007-04-05 01:03:57 · answer #3 · answered by dharmabum2 2 · 1⤊ 0⤋
Let the numbers be denoted by a, b, c, d and e respectively.
Thus, (a+b+c+d+e)/5=30
=> a+b+c+d+e= 150
and (a+b+c+d)=25*4=100
=>100+e=150
=>e=50
Thus the fifth number is 50
2007-04-07 11:49:10 · answer #4 · answered by Anonymous · 0⤊ 0⤋
.Average of 5 numbers = 30
Sum of numbers = Average à Total numbers
Therefore sum of 5 numbers = 30 Ã 5 = 150
Similarly sum of 4 numbers = 25 Ã 4 = 100
Therefore 5 th number = 150 – 100 = 50
2007-04-05 03:52:21 · answer #5 · answered by Pranil 7 · 0⤊ 0⤋
If the average of 5 numbers is 30, then their sum is 150. If the average of 4 numbers if 25, then their sum is 100. 150 - 100 = 50
2007-04-05 01:00:19 · answer #6 · answered by msmthtchr 3 · 1⤊ 0⤋
50 25+25+25+25+50/5=30
2007-04-05 00:59:50 · answer #7 · answered by phoenixparalysis 2 · 0⤊ 0⤋
50 -- In the first case 5 * 30 = 150 and in the second, 4 * 25 = 100. The difference is the missing fifth number, so 150 - 100 = 50.
good luck!
2007-04-05 00:59:15 · answer #8 · answered by birdwoman1 4 · 0⤊ 0⤋
sum of 5 numbers=30*5=150
sum of 4 numbers=25*4=100
5 th number=150-100=50
2007-04-05 08:20:08 · answer #9 · answered by manarshh_jot 2 · 0⤊ 0⤋
Sum of 5 numbers/5=30 ..ie sum of 5 numbers is 30x5=150
Sum of 4 numbers /4=25....ie sum of 4 numbers is 25x4=100
The difference is the 5th number ,
ie 150-100=50.
2007-04-05 01:38:43 · answer #10 · answered by suriapandi s 2 · 0⤊ 0⤋