Question

Q4.Shirley scored 68 marks and for her first Math test and 85 for her second Math
test. What is the minimum mark she is required to score for her third test to
meet her target of obtaining an average of 80 marks or more for the test?​

Answer 1

Answer:

Let take third test marks will be x

so , 68+85+x / 3 =80

then,68+85+x=80×3

153+x=240

x=240-153

x=87

Hence,87 is marks in third test for complete average marks of 80

Answer 2

Given:-

• First Test = 68 marks
• Second test = 85 marks
• Average = 80

━━━━━━━━━━━━━━━

Need to find:-

• Third test marks = ?

━━━━━━━━━━━━━━━

Solution:-

Let:

• The marks scored by Shirley at 3rd test be = x

Given, average of three marks = 80 or more

→$\dfrac{68 + 85 + x}{3} \geqslant 80$

→$68 + 85 + x \geqslant 80 \times 3$

→$68 + 85 + x \geqslant 240$

→$153 + x \geqslant 240$

→$x \geqslant 240 - 153$

$\red{\boxed{\bold{\large{\implies x \geqslant 87}}}}$

Therefore, Shirley should score 87 marks or more in her third maths exam to get an average of 80 or more .