Aptitude - Average - Discussion

Please explain me this more clearly anyone.

Hi Julie,

In a 30 days month you will get 5 sundays if the 1st day is sunday.

So 5 sundays x 510 = 2550

Remaining 25 days X 240 days =6000.

So 2550 +6000= 8550/30 = 285.

30/7= 28days+2 odd days
in 28 days 4 days are sunday.
out of 2 odd days 1 day is sunday.
so number of sundays are 5.
remaining days other than sunday=30-5=25.
so total no of visitors for a month=(510*5)+(240*24)=8550.
so average,
8550/30=285.

30 Day's so,
30/7 = 28 + 2 day's so, 4 week's +2 days.
S m t w th f sat
S m t w th f sat
S m t w th f sat
S m t w th f sat
S m
5 sunday's
25 other day's

5*510 = 2550
25*240 = 6000

(6000+2550)/30= 285.

OMG!!! I bow to all those who understand maths>>>. Its a real treasure and talent.

I wish that every month should start from sunday. ;).

This is not true. In 30 days, 1st day being Sunday, there are 5 Sundays, ending at 28th day, but there are 5 Mondays and 5 Tuesdays as well (29th and 30th day respectively).

So in order for the average number of visitors on Monday to be 240, the number of Monday visitors in the whole month must be (240*5) = 1200.

So is it with Tuesday - the average number of Tuesday visitors equals (240*5) = 1200.

Those Monday and Tuesday are 29th and 30th days of the given month respectively.

So the number of other days of the week equals 4.

There are 4 Wensedays, 4 Thursdays, 4 Fridays, and 4 Saturdays.

In order for the average number of visitors of each of these days to be equal to 240, each of these days must have taken (240*4)= 960 visitors per month.

So the whole number of visitors per month:= 2550 (Sundays) + 1200 (Mondays) + 1200 (Tuesdays)+ 960 + 960 + 960 + 960 = 8790.
Not 8550 !!!

So the average that we've been solving for is equal to 293. Not 285 !!!

Let see

510 visitors on Sundays
240 on other days
finding the no. of visitors in a month of 30 days starting with Sunday.
7 days= 1 week

Therefore in a week, we have 510*1 + 240*6=1950 visitors

There are 4 weeks and 2 days in a 30 day month
therefore we get 4 weeks=1950x4=7800 and

2 days beginning with a sunday which means sunday and any other day, gives us 510 + 240=750

Therefore average attendants in a month=(7800+750)/30= 285

If a Month starts from Sunday, there will be 5 Sundays.

So 5 Sundays total Number of visitors= 5*510=2550
Remaining days visitors= 25*240=6000 visitors
Total number of visitors for 30 days= 2550+6000= 8550 visitors
Avg number of visitors per day= 8550/30days =285visitors

@Ibrahim:

You are right in logic but you missed the trick.

A month of 30 days starting with Sunday have only 5 Sunday & 5 Monday but not 5 Tuesday.

Look, if you go through the following, you can understand where you are wrong.

Count of Sunday:

Day 1> Day 8> Day 15> Day 22> Day 29.

Therefore, Day 29 is the last Sunday of that month, so if you proceed further, then Day 30 is your final Monday.

You don't have any further 5th Tuesday in this context.

Now you can table your calculation like what you did earlier without counting the non-existing last Tuesday.

So the whole number of visitors per month:= 2550 (Sundays) + 1200 (Mondays) + 240*4(Tuesday) + 960 + 960 + 960 + 960 = 8550.

That is the right answer you will get !