A study was conducted to find out the concentration of sulphur dioxide in the air in parts per million (ppm) of a certain city. The data obtained for 30 days is as follows :
For how many days, was the concentra-tion ofsulphur dioxide more than 0.11 parts per million.

A study was conducted to find out the concentration of sulphur dioxide in the air in parts per million (ppm) of a certain city. The data obtained for 30 days is as follows : Make a grouped frequency distribution table for this data with class intervals as 0.00 - 0.04, 0.04 -0.08 and so on.

In a primary school, the parents were asked about the number of hours they spent per day in helping their. Children to do home work. There were 90 parents who helped for (1)/(2) hour to 1(1)/(2) hours. The distribution of parents according to the time for which, they said they helped is given in the figure below : 20% helped for more than 1 ""1//2 hours per day, 30% helped for (1)/(2)" hour to "1 (1)/(2) hours, 50% did not help at all. Using this, answer the following: How many said that they helped for more than 1 (1)/(2) hours?

In a primary school, the parents were asked about the number of hours they spent per day in helping their. Children to do homw work. There were 90 parents who helped for (1)/(2) hour to 1(1)/(2) hours. The distribution of parents according to the time for which, they said they helped is given in the figure below : 20% helped for more than 1 ""1//2 hours per day, 30% helped for (1)/(2)" hour to "1 (1)/(2) hours, 50% did not help at all. Using this, answer the following: How many parents were surveyed?

In a primary school, the parents were asked about the number of hours they spent per day in helping their. Children to do homw work. There were 90 parents who helped for (1)/(2) hour to 1(1)/(2) hours. The distribution of parents according to the time for which, they said they helped is given in the figure below : 20% helped for more than 1 ""1//2 hours per day, 30% helped for (1)/(2)" hour to "1 (1)/(2) hours, 50% did not help at all. Using this, answer the following: How many said that they did not help?