The mean and s.d. of height readings of a group of employees of a firm are found to be 172 cm and 18 cm. While the same measure of their weight readings are 65 kg and 9 kg. Compare the variability of the height readings with that of the weight readings.

The length, breadth and height of a cuboidal piece of ice are 40 cm, 25 cm and 15 cm respectively. If the weight of ice be 9/10 part of water of same volume and the weight of lee water be 1 gm, then what will be the weight of the total piece of ice ?

The height of my friend Priya is 160 cm and the height of her mother is 170 cm. Again Priya's weight is 40 kg and her mother's weight is 42.5 kg. Let's find if their weights are in proportional to their heights.

The weight of a wooden box made of wooden planks with the thickness of 5 cm along with its covering is 115·5 kg. But the weight of the box filled with rice is 880·5 kg. The length-and breadth of inner side of the box are 12 dcm and 8·5 dcm respectively and the weight of 1 cubic dcm rice is 1 ·5 kg. Determine the inner height of the box. Also determine the total expenditure to colour the outside of the box, if the rate is ₹ 1 ·50 per sq-dcm.

Charles Richter defined the magnitude of an earthquake to be M = log_(10) (I/S) , where I is the intensity of the earthquake (measured by the amplitude of a seismograph reading taken 100 km from the epicentre of the earthquake) and S is the intensity of a ''standed earthquake'' (whose amplitude is 1 micron =10^(-1) cm). Each number increase on the Richter scale indicates an intensity ten times stronger. For example. an earthquake of magnitude 5. An earthquake of magnitude 7 is 100 times stronger then an earthquake of magnitude 5. An earthquake of magnitude 8 is 1000 times stronger than an earthquake of magnitude 5. The earthquake in city A registered 8.3 on the Richter scale. In the same year, another earthquake was recorded in city B that was four times stronger. What was the magnitude of the earthquake in city B ?

A weight of 200 kg is repeatedly dropped freely from a height of 10 m, on the head of a pole of mass 50 kg, to push it into the ground. For every impact, the pole penetrates 7 cm into the ground. Find the average resistance of the ground.

The mean and S.D. of 20 items were found to be 12 and 6 respectively. On checking it was discovered that items which should correctly read as 11 and 21 had been wrongly taken as 15 nd 27 respectively. Find the correct values of mean and S.D.