Question

13. If the sum of a few numbers is 450 and their mean is
50 and if another number 100 is included, the mean
would become
(a) 55
(b) 60
(c) 75
(d) 150
14. A tradesman sold an article at a loss of 20%. If the
selling price had been increased by 100, there
would have been a gain of 5%. What was the cost
price of the article?
(a) 400
(b) 500
(c) * 600
(d) 300​

Answer 1

Ans 13):- 55

⇒sum of a few numbers is 450

⇒Let the number of observation (here numbers)  be = n

⇒ mean = 50

So  Mean = sum of observation/number of observation

i.e 50 = 450/n

n = 9

⇒ Now another 100 is added to these 9 observation so total number of observation = 10

⇒ Sum of observation becomes = 450+100 = 550

⇒ So New mean = 550/10 = 55

Answer 2

Answer:

Step-by-step explanation:

sum of x numbers =450

mean of x numbers= 450/x =50

thus, x = 9

if 100 is added to 450, new sum = 450+100=550

new mean = 550/10

=55 ans