Respuesta :
Answer:
a score of 100 is required
Step-by-step explanation:
the average is calculated as
average = [tex]\frac{sum}{count}[/tex]
given her average for 4 subjects is 80 , then
[tex]\frac{sum}{4}[/tex] = 80 ( multiply both sides by 4 to clear the fraction )
sum = 320
let x be the score required to raise average to 84 , then
[tex]\frac{320+x}{5}[/tex] = 84 ( multiply both sides by 5 )
320 + x = 420 ( subtract 320 from both sides )
x = 100
she requires to score 100 in her fifth subject
Answer: she needs score 100 in the fifth subject.
Step-by-step explanation:
Let a subject is nₓ
Hence,
[tex]\displaystyle\\\frac{n_1+n_2+n_3+n_4}{4} =80\\[/tex]
Multiply both parts of the equation by 4:
[tex]n_1+n_2+n_3+n_4=(80)(4)\\n_1+n_2+n_3+n_4=320[/tex]
[tex]\displaystyle\\\frac{n_1+n_2+n_3+n_4+n_5}{5}=84[/tex]
Multiply both parts of the equation by 5:
[tex]n_1+n_2+n_3+n_4+n_5=(84)(5)\\(n_1+n_2+n_3+n_4)+n_5=420\\320+n_5=420\\320+n_5-320=420-320\\n_5=100[/tex]
