Quantitative Aptitude

Averages

1,527 Questions

All Basic average and reverse calculation 405 Adding or removing an observation 342 Weighted and combined averages 320 Replacement and correction of a recorded value 233 Ratio shortcut for two-group mixtures 111 Equal-distance average speed 59 Age, score, weight, and spending applications 32 Consecutive terms and arithmetic progressions 25

Averages Questions

Multiple choice

In a polymer sample $30\%$ of molecules have a molecular mass of $20,000$, $40\%$ have $30,000$ and the rest $60,000$. What is the weight average molecular mass of the polymer?

$40,300$
$30,600$
$43,333$
$50,400$

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Multiple choice

The average age of $14$ girls in a class is $20$ years and of $18$ boys is $23$ years. Find average age of class.

$21\, \frac{11}{16}$ years
$21\, \frac{9}{16}$ years
$21\, \frac{7}{16}$ years
$21\, \frac{13}{16}$ years

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Multiple choice

If a sales person sell electric appliance on an average of $6$ appliances per day f or the first two weeks. The dot plot is drawn to find out how much he sold in first $13$ days. What is the minimum number of appliances he must sell on the $14^{th}$ day in order to reach his goal?

$5$
$6$
$7$
$8$

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Multiple choice

The average weight of $3$ persons is $65$kg. If a fourth person having a weight of $45$kg joins the group, then what is the average weight of the group?

$65$ kg
$63$ kg
$61$ kg
$60$ kg

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Multiple choice

Average scores of fifty students in a class is $ 44$. Later on it was found that a score $ 23 $ was incorrectly recorded as $ 73$. The correct average score is

$42$
$43$
$45$
$44$

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Multiple choice

The average marks, in a class of $30$ students, are found to be $45$. On checking two mistakes were found. After correction, if one student got $45$ marks more and another students got $15$ marks less, then the correct average marks are

$45$
$44$
$47$
$46$

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Multiple choice

The average age of $45$ persons is decreased by $\cfrac 19$ year when one of them having $60$ years is replaced by a new comer. Then, the age of the new comer is

$48$ years
$46$ years
$50$ years
$55$ years

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Multiple choice

Rachna had an average score of $45$ from $6$ test. Her teacher dropped her lowest score, which is $30$ and calculated the average of the remaining scores to decide her grade. Which of the following gives her new average score?

$\cfrac { \left( 45\times 5-30 \right) }{ 5 } $
$\cfrac { \left( 45\times 5-30 \right) }{ 6 } $
$\cfrac { \left( 45\times 6-30 \right) }{ 5 } $
$\cfrac { \left( 45\times 6-30 \right) }{ 6 } $

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Multiple choice

The mean or average number of heads when we toss $10$ unbiased coins is

$20$
$10$
$5$
$15$

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Multiple choice

The average runs of two groups is $57$. The mean of the first group is $52$ and the mean of the second group is $60$. The proportion of ______.

$3 : 5$
$2 : 5$1
$2 : 8$
$5 : 2$

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Multiple choice

A school has four sections of chemistry in class XII having $40, 35, 45$ and $42$ students. The mean marks obtained in Chemistry test are $50, 60, 55$ and $45$ respectively for the four sections. The overall average of marks per students is -

$53$
$43$
$55.3$
$52.25$

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Multiple choice

The marks obtained by a student of class X in first and second unit test are $35$ and $21$ respectively. Find the minimum marks he should get in the annual examination to have an average of at least $30$ marks

$\displaystyle x\leq 34$
$\displaystyle x\geq 34$
$x > 34$
$x < 34$

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Multiple choice

The average weight of 29 students is 28 kg. By the admission of a new student the average weight is reduced to 27.8 kg. The weight of the new student is

22 kg
21 kg
22.4 kg
21.6 kg

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Multiple choice

Tara's three bowling scores in a tournament were $167, 178$, and $186$. What was her average score for the tournament?

$176$
$177$
$178$
$179$
$180$

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Multiple choice

In an examination, $40\%$ of the candidates wrote their answer in Hindi and the others in English. The average marks of the candidates written in Hindi is $74$ and the average marks of the candidates written in English is $77$. What is the average marks of all the candidates?

$75.5$
$75.8$
$76.0$
$76.8$

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