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Rangi ya buti

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Wakuu... salam kwenu. Kama kichwa cha habar kinavyonieleza kuna swali limekuwa changamoto kwetu..Natumain hapa JF litapata jibu... KARIBUNI

In a form 4 class there are boys and girls. The mean mark in mathematics test for the whole class is 35.5. If the mean mark for the 15 girls is 28 and mean marks for boys is 40, Determine the number of studentsin class.
 
[emoji124] [emoji124] [emoji124] napita
 
Hii si set mkuu ama?

Hakuna simple questions kama set....
 
Swali lako ni jepesi Sanaa mtt wa 3m anafanya
 
Number of boys =25,
Number of girl=15, so total no of student 25+15=40

Tumia formular ya combined mean kutafuta no of boys

Nimeshindwa kuiandika apaaa
 

This question is as simple as abcd but it suffers from the flaws of either ambiguity or is very poorly phrased

Look here:
"If the mean mark for the 15 girls is 28 and mean marks for boys is 40,"

The above quote suggests that there only 15 girls in the class.
Possibly, if there are more than 15 girls, a normal mathematician would expect the following statement (the bold word FIRST word was important here)

If the mean mark for the FIRST 15 girls is 28

In other words, if there are only 40 boys, the statement .......... "and mean marks for boys is 40," was supposed to read
........... "and the mean mark OF ALL boys is 40, (the word for was supposed to be replaced by the bold words OF ALL) so that your question was supposed to read as follows:

In a form 4 class there are boys and girls. The mean mark in a mathematics test for the whole class is 35.5. If the mean mark for the FIRST 15 girls is 28 and THE mean marks OF ALL boys is 40, determine the TOTAL number of students in the class

But as it is now, the phrasing of your language in your question suggests that there are 15+40=55 students in the class, which is actually not the answer you intended. Please try to be a mathematician!

However, I will come back with the solution of your question as I have rephrased it myself, as I'm sure that is what you intended to ask
 
Average=Total/number

Therefore Total=Average X number

Girls: Total=average x number
=28x15=420

Boys:total=average x number
=40 x y=40y

Combiné total=420+40y

Now Average=total/number
35.5=(420+40y)/(15+y)

35.5(15+y)=420+40y
532.5+35.5y=420+40y
535.5-420=40y-35.5y
112.5=4.5y
25=y

Number of boys=25

Total number is 25+15=40
 
DG necta hwatoagi maswali kama haya ya ******* achana nalo!!!
 

In a form 4 class there are boys and girls. The mean mark in a mathematics test for the whole class is 35.5. If the mean mark for the FIRST 15 girls is 28 and THE mean mark OF ALL boys is 40, determine the TOTAL number of students in the class

Dear Rangi ya buti


Attached (in pdf) is a solution the problem

The number of students in the class is
Girls 15+n;
Boys 15+n; so that the total number is N such that

N=30+2n; where n=1, 2, 3, 4, 5, ...............
 

Attachments

here is the simple solution;
let the number of student in the whole class be x;
((15*28)+(40*(x-15))/(15+(x-15))=35.5
upon mathematical manipulation,x=40;
:. number of student in the whole class is 40;
 
dimaa said:
Hii ni set, kakukoroga habari za mean mark
Click to expand...
Ivii we jamaa unaijua set vizur,,, hiii n statistics kipengere cha determination of mean, s deviation and variance of combained item,,,,,,, chukua chand advanced mathematics utakutana na maswali ya aina hiyoooo
 
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