A student's average ( arithmetic mean) test score on 4 tests is 78. What must be the students score on a 5th test for the students average score on the 5th test to be 80?

• 5 * 80 = 400; 4 * 78 = 312 5th = 400 - 312 = 88;
• 12 years agoHelpfull: Yes(15) No(0)
• 4 tests sum=78*4=312
  5 tests sum=80*5=400
  then 5th test score=400-312=88
  Ans: 88
• 12 years agoHelpfull: Yes(11) No(0)
• 78*4+80/5=88
• 12 years agoHelpfull: Yes(4) No(0)
• avg f 4 test =78...therfr 78*4=312
  lt x b d scr f 5th test
  so, (312+x)/5=80;
  x=88
• 12 years agoHelpfull: Yes(3) No(0)
• he must score 88 on 5th exam
• 12 years agoHelpfull: Yes(2) No(0)
• ans:88
  
  the average is 80. so he should score 80
  but remaining 4persons are less than2.so they are 8marks less than team average.5th student have to cover that.so,80+8=88
• 12 years agoHelpfull: Yes(1) No(0)
• 78*4+80/5=88
• 10 years agoHelpfull: Yes(0) No(0)
• Sum of 4 tests = 78 x 4 = 312
  Average score to be 80, so sum= 80 x 5 = 400
  Score in 5th test = 400 - 312 = 88
• 4 years agoHelpfull: Yes(0) No(0)
• 80-78=2; 2*4 = 8; new average(80) + 8 = 88;
  explanation:
  4th test average is 78, 5th test average is 80, every test it is increased by 2;
  overall average increase for all the 4 test is 8; this 8 is given by 5th test ; so give it back to get 5th test score 80+8=88.
• 4 years agoHelpfull: Yes(0) No(0)