The average weight of 29 students is 28 kg. By the admission of a new student, the average weight is reduced to 27.8 kg. The weight of the new student is :

a. 22 kg
b. 21.6 kg
c. 22.4 kg
d. 21 kg

• a) 22 kg
  Expalnation - if its weight is 28 kg then no change on average but the average reduced so its weight is less than 28,and we know that 0.2 reduction take place So it will be distributed among all 30 so
  0.2*30=6kg less than average.
• 8 years agoHelpfull: Yes(1) No(0)
• Weight of new student = Total weight of all 20 students - Total weight of initial 19 students
  = (30 x 27.8 - 29 x 28) kg
  = 22 kg.
  
  ans ) a
• 8 years agoHelpfull: Yes(0) No(0)
• = Increased Average (+ or -) No of old persons * increase or decrease in average
  = 27.8 - 29*0.2 = 22
• 8 years agoHelpfull: Yes(0) No(0)
• 22 A option
• 7 years agoHelpfull: Yes(0) No(0)
• Here, weight of the new student is added and final average of the group decreases..
  Therefore, Change in average is (-)ve, using the formula.
  Sum of quantities added = { Change in nos of Quantities * Original Average } - { Change in average * Final nos of Quantities }
  => Weight of new student = ( 1 * 28 ) - ( 0.2 * 30 ) = 22kg
  Therefore, Weight of new student is 22kg.
• 4 years agoHelpfull: Yes(0) No(0)