The average of first three numbers is double of the fourth numbe

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 Multiple Choice QuestionsMultiple Choice Questions

31.

The average (arithmetic mean) of 330, 360 and 390 is

  • 327 + 357 + 387

  • 360

  • 329+359+389

  • 329+359+389

327 Views

32.

The average of the largest and smallest 3 digit numbers formed by 0, 2 and 4 would be

  • 312

  • 213

  • 222

  • 222

260 Views

33.

The frequency distribution data is given below. If the average age is 17 years, the value of m is 
Age (in m years) :   8       20       26        29
Number of people:   3        2        m         1

  • 1

  • 2

  • 3

  • 3

206 Views

34.

The average monthly expenditure of a family for the first four months is ₹ 2570, for the next three months ₹ 2490 and for the last five months ₹ 3030. If the family saves ₹ 5320 during the whole year, the average monthly income of the family during the year is

  • ₹ 3000
  • ₹ 3185
  • ₹ 3200
  • ₹ 3200
273 Views

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35.

The average of six numbers is 20. If one number is removed, the average becomes 15. What is the number removed?

  • 5

  • 35

  • 112

  • 112

193 Views

36.

After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. The difference between the ages of the replaced and the new members is

  • 2 years

  • 4 years

  • 8 years

  • 8 years

170 Views

37.

A man spends ₹ 1800 monthly on an average for the first four months and ₹ 2000 monthly for the next eight months and saves ₹ 5600 a year. His average monthly income is

  • ₹ 2000

  • ₹ 2200

  • ₹ 2400

  • ₹ 2400

131 Views

38.

The arithmetic mean of the following numbers
1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6 and 7, 7, 7, 7, 7, 7, 7, is

  • 4

  • 5

  • 14

  • 14

165 Views

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39.

The average of first three numbers is double of the fourth number. If the average of all the four numbers is 12. find the 4th number.

  • 16

  • 48 over 7
  • 20

  • 20


B.

48 over 7

Let a, b, c, d be the four numbers.
rightwards double arrow space space fraction numerator straight a plus straight b plus straight c over denominator 3 end fraction space space equals space 2 straight d
rightwards double arrow space space straight a space plus space straight b space plus space straight c space equals space 6 straight d space space space space space space space space space space space... left parenthesis straight i right parenthesis
therefore space space space space space space fraction numerator straight a plus straight b plus straight c plus straight d over denominator 4 end fraction space equals space 12

rightwards double arrow space space space straight a plus straight b plus straight c plus straight d space equals space 48
rightwards double arrow space space space 6 straight d space plus space straight d space space equals space 48
rightwards double arrow space space space space 7 straight d space space equals space 48
rightwards double arrow space space space space space straight d space equals space 48 over 7

129 Views

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40.

If the average of 6 consecutive even numbers is 25, the difference between the largest and the smallest number is

  • 8

  • 10

  • 12

  • 12

249 Views

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