Average - Study Mode

[#156] A cricketer whose bowling average is 12.4 runs per wicket, takes 5 wickets for 26 runs in the next innings and thereby decreases his average by 0.4. The number of wickets taken by him till the last match was
Correct Answer

(C) 90

Explanation

Solution: According to the question, The number of wickets taken by him till the last match was = 85 + 5 = 90

[#157] In a class of 60 students, 40% are girls. The average weight of the boys is 62 kg and that of the girls is 55 kg. What is the average weight of the whole class?
Correct Answer

(A) 59.2 kg

Explanation

Solution: Total weight = 36 × 62 + 24 × 55 = 2232 + 1320 = 3552 Average = $$frac{{3552}}{{60}}$$xa0= 59.2 kg

[#158] The average of 25 numbers is 64. The average of the first 13 numbers and that of the last 13 numbers are 62.8 and 72.2, respectively. If the 12 th number is 61, and if the 12 th and 13 th numbers are excluded, then what is the average of the
remaining number (correct to one decimal place)?
Correct Answer

(C) 60.2

Explanation

Solution: Average of 25 numbers = 64 Sum of 25 numbers = 64 × 25 = 1600 Average of first 13 numbers = 62.8 Sum of first 13 numbers = 62.8 × 13 = 816.4 Average of last 13 numbers = 72.2 Sum of last 13 numbers = 72.2 × 13 = 938.6 13 th number = 816.4 + 938.4 - 1600 = 1754.8 - 1600 = 154.8 12 th number = 61 If we remove 12 th and 13 th number then, sum of remaining numbers = 1600 - 61 - 154.8 = 1384.2 Average $$ = frac{{1384.2}}{{23}} = 60.18 sim 60.2$$

[#159] Average of 7 consecutive odd numbers is 31. If the previous and next odd number to these 7 odd numbers are also included, then what will be the new average?
Correct Answer

(B) 31

Explanation

Solution: ∵ Average of 7 consecutive odd numbers = 31 ∴ Mid odd number = fourth term = 31 So, seven consecutive number [ = x08egin{array}{*{20}{c}}
{25}&{27}&{29}&{31}&{33}&{35}&{37} \
leftarrow & leftarrow & leftarrow &{}& o & o & o \
{ - 2}&{ - 2}&{ - 2}&{}&{ + 2}&{ + 2}&{ + 2}
end{array}] According to the question, Previous number will be = 25 - 2 = 23 And next odd number will be = 37 + 2 = 39 Average $$ = frac{{23 + 39}}{2} = frac{{62}}{2} = 31$$ ∴ Average will remain same because 2 subtracted in previous and 2 added in the next number.

[#160] There is a number consisting of two digits, the digit in the unit's place is twice than digit in the ten's place and if 2 subtracted from the sum of the digits, the difference is equal to $${frac{1}{6}^{{ ext{th}}}}$$ of the number. The number is-
Correct Answer

(D) 24

Explanation

Solution: Shortcut method: Do by option Let the number be 24 Sum of digits = 2 + 4 = 6 ⇒ 6 - 2 = $$frac{1}{6}$$ × 24 = 4 = 4 matched So, 24 is answer