ibps-so 2018 · Question 161 of 356

The o cer who kept the record of the sitting jotted down the ve statements given below as the meeting rose, and only one of them was found afterwards to agree with the seating. Which one of the following statements is true of the arrangement that has been arrived at?

1. AMunmun sits immediately to the left of Bakul
2. BThe o cer who handles muslin faces towards the centre of the table
3. CShefali handles denim and faces away from the centre of the tableCorrect
4. DExactly two of the o cers sit between Peeyush and Daulat
5. ELoknath and Indresh face one and the same direction Directions (Q76–Q82) : The passage that follows is taken from a discussion of prediction and of the uses to which the public puts it, a question that has passed in recent years out of the scienti c journals and into common argument. Read the passage carefully and answer the questions given below it. Certain words have been printed in bold in order to help you to locate them while answering some of the questions. Your answers are to be founded upon the passage alone. A weather forecast is a peculiar sort of statement. It is arrived at by reasoning of considerable rigour, and it is judged by the public against a single event, in a single place, on a single afternoon. The listener who is told that there is a forty per cent chance of rain hears a promise; when the promise is broken he concludes that forecasting is guesswork dressed up in the vocabulary of a science. The di culty is not that the laws governing the atmosphere are unknown. They have been set down as equations for something like a hundred years now, and a computer can be made to solve them. The di culty is that the laws must be applied to a starting state, and the starting state can never be known exactly. Instruments are placed where people happen to live; over the oceans and the deserts there are stretches in which almost nothing is measured, and between one station and the next the model must interpolate. Worse, the equations are of a kind in which an in nitesimal di erence at the beginning does not stay small. Two calculations begun from states that no instrument could tell apart will, within a week, describe two di erent sorts of weather. This is not a aw in the model. It is a property of the atmosphere itself, and no improvement in computing will abolish it. Meteorology has responded by changing the shape of its answer. Instead of one calculation, the model is run many times over from starting states that di er within the margin of measurement, and the forecaster reports the proportion of those runs in which rain arrives. The percentage is not a hedge and not an evasion. It is the whole of what the computation has to say, stated without embellishment. What the public wants, and what a headline requires, is a categorical answer. A forecaster who names a probability and is then contradicted by the afternoon is held to have been wrong, although no single afternoon can refute a statement of that kind; only a long series can. The proper test is calibration: taking every occasion on which forty per cent was announced, rain should have fallen upon about forty of every hundred. Where an institution judges its forecasters by individual outcomes rather than by that record, it teaches them to speak with a con dence the calculation does not warrant, which is the one failure from which there is no recovering. The record of improvement is nonetheless remarkable. A forecast issued three days ahead today is about as reliable as a forecast issued one day ahead was to our grandparents, and the gain has come from satellites that observe what no ground station could, from computing power, and from the deliberate treatment of uncertainty rather than from any revision of the underlying physics. The moral travels well beyond meteorology. Wherever a system is sensitive to its own initial state and is observed imperfectly – an epidemic, a harvest, an economy – the useful forecast is a distribution and the useless one is a single number. The demand for the single number is seldom a demand for information. It is a demand to be told a story.