In a primary school, the parents were asked about the number of hours they spend per day in helping their children to do homework. There were 90 parents who help for \[\frac{1}{2}\]hr to\[1\frac{1}{2}\]hr. The distribution of parents according to the time for which, they said they helped is given in the adjoining figure, 20% helped for more than 1-hr per day. 30% helped for \[1\frac{1}{2}\] hr to \[1\frac{1}{2}\]hr; 50% did not help at all Using this, answer the following : |
(a) How many parents were surveyed? |
(b) How many said that did not help? |
(c) How many said that they helped for more than \[1\frac{1}{2}\] hours? |
Answer:
Let us suppose that there are x parents. 90 parents who help for \[\frac{1}{2}\]hr to \[1\frac{1}{2}\]hr. They show the percentage is 30%, then according to formula. Percentage value = The percentage of whole value 90 = 30% of x \[90=\frac{30x}{100}\] \[\frac{90\times 100}{3}=x\] x = 300 There are 300 parents: 20% helped for more than\[1\frac{1}{2}\] hr. per day. Again, according to condition, Percentage value = Percentage of whole value = 20% of x \[=\frac{20}{100}\times 300\] Percentage value = 60 parents who helped their children more than \[1\frac{1}{2}\] hr per day 50% did not help at all. Again, using formula, Percentage value = Percentage of whole value = 50% of x \[=\frac{50}{100}\times 300\] Percentage value = 150 parents did not help at all (a) 20% helped for more than \[1\frac{1}{2}\] hr per day + 30% helped for \[\frac{1}{2}\] hr to \[1\frac{1}{2}\] hr per day = The value of 20% + The value of 30% + The value of 50% + 50% did not help = 60 parents who help their children more than\[1\frac{1}{2}\]hr. + 90 parents who help their children \[\frac{1}{2}\] hr to\[1\frac{1}{2}\] hr. + 150 parents who did not help = 300 parents who help their children (b) The value of 50% parents they said did not help = 150 (c) The value of 20% who said that they help their children more than \[1\frac{1}{2}\] hr = 60 parents
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