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Averages 1/7

37. The average temperature of the first three days is $27^\circ $C and that of the next three days is $29^\circ $C. If the average of the whole week is $28.5^\circ $C, the temperature of the last day of the week is :
a. $10.5^\circ C$
b. $21^\circ C$
c. $31.5^\circ C$
d. $42^\circ C$


38. The average age of 30 students in a class is 12 years. The average age of a group of 5 of the students is 10 years and that of another group of 5 of them is 14 years. The average of the remaining students is :
a. 8 years
b. 10 years
c. 12 years
d. 14 years


39. The average of 8 numbers is 21. If each of the number is multiplied by 8, the average of the new set of numbers is :
a. 8
b. 21
c. 29
d. 168


40. The average of 50 numbers id 38. If two numbers, namely 45 and 55 are discarded, the average of the remaining numbers is :
a. 36.5
b. 37.0
c. 37.5
d. 37.52


41. The average height of 30 girls out of a class of 40 is 160 cm. and that of the remaining girls is 156 cm. The average height of the whole class is :
a. 158 cms
b. 158.5 cms
c. 159 cms
d. 159.5 cms


42. A batsman had a certain average of runs for 16 innings. In the 17th innings, he made a score of 87 runs thereby increasing his average by 3. What is his average after 17 innings?
a. 39
b. 38
c. 37
d. 36


43. Some consecutive natural numbers, starting with 1, are written on the board. Now, one of the numbers was erased and the average of the remaining numbers is 800/39. Find the number which was erased.
a. 24
b. 20
c. 18
d. 16


44. Two vessels contain mixture of milk and water in the ratio of 5 : 2 and 3 : 1 respectively. Find the ratio of milk and water in the new solution, if two mixtures are mixed in equal amount.
a. 41 : 15
b. 39 : 17
c. 39 : 14
d. 15 : 41


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