4. Out of three numbers, the first is twice the second and is half of the third. If the average of the three numbers is 56, the three numbers in order are :

5. The average of 50 numbers is 38. If two numbers, namely 45 and 55

6. The average height of 30 girls out of a class of 40 is 160 cms, and that of the remaining girls is 156 cms. The average height of the whole class is :