Question

the average of 5 number is 30...four numbers are 35, 40,20,25 . what is the fifth number?​

Answer 1

Answer:

30

Step-by-step explanation:

Let the fifth number be x.

Average of 5 numbers = 30

Sum of 5 numbers = 30 × 5 = 150

35 + 40 + 20 + 25 + x = 150

120 + x = 150

x = 150 - 120

x = 30

Therefore, the fifth number is 30.

Answer 2

Answer:

$\purple{ \underline{ \boxed{\sf { \red{ Fifth \: number \: is \: 30 \: .}}}}}$

Step-by-step explanation:

$\purple{ \bigstar \underline{ \boxed{\sf {Given \colon}}}}\\ \sf\red{ Average \: of \: five \: numbers \: is \: 30 \: .} \\ \sf \red{Given \: four \: numbers \: are \: 35,40,20 \: and \: 25 \: .} \\\purple{ \bigstar \underline{ \boxed{\sf {To \: find \colon}}}} \\ \sf \red{Fifth \: number \: .} \\ \purple{ \bigstar \underline{ \boxed{\sf { Solution\colon}}}}\\ \red{ \sf{Let \: 5th \: number \: be \: x}}\\ \purple{\sf{Average = \frac{Sum \: of \: all \: observations }{ Total \: number \: of \: observations} }} \\ \red{\sf{Average = \frac{35 + 40 + 20 + 25 + x}{5} }} \\ \red{ \sf{30 = \frac{120 + x}{5} }} \\ \red{ \sf{30 \times 5 = 120 + x}} \\ \red{ \sf{150 = 120 + x}} \\ \red{ \sf{120 + x = 150}} \\ \red{ \sf{x = 150 - 120}} \\ \red{ \sf{x = 30}} \\ \purple{ \underline{ \boxed{\sf { \red{\therefore \: Fifth \: number \: is \: 30 \: .}}}}}$