第12章百分比–练习12.2 |套装1
问题14.锡和铜的合金由15份锡和105份铜组成。查找合金中铜的百分比?
解决方案：
Given, number of Tin parts = 15
The number of Copper parts = 105
So, total parts = 105 + 15 = 120
So, the percentage of Copper part = (105/120) × 100 = 87.5%
Hence, the percentage of Copper in an alloy is 87.5%
问题15.合金包含32％的铜，40％的镍和其余的锌。在1千克合金中找到锌的质量。
解决方案：
Given, the percentage of copper = 32 %
The percentage of nickel; = 40 %
So, the percentage of Zinc = 100 % -(32 % + 40 %) = 28 %
So, we can say the mass of zinc in 1 kg alloy = 28 % of 1 kg or 1000 gm
= (28/100) × 1000 = 280 grams
Hence, the mass of Zinc in 1 kg alloy is 280 gm
问题16：一名驾车者在他的第一站停了下来，走了122公里。如果他现在有10％的旅程要完成，那么整个旅程要花多长时间?
解决方案：
Given, the distance travelled by motorist before stopping = 122 km
Let a km be the total length of the whole journey
So, 10 % of a = 122 km
(10/100) × a = 122
a = 1220 km
Hence, the length of the whole journey is 1220 km
问题17：某所学校有300名学生，其中142名是男生。它有30名老师，其中12名是男性。在学校的学生和老师总数中，女性占百分之几?
解决方案：
Given, Total students = 300
Total number of boys = 142
So, the number of girls = 300 – 142 = 158
Total number of teachers = 30
Number of male teachers = 12
So, the number of female teachers = 30 – 12 = 18
So, total number of females are = 158 + 18 = 176
And total number of teachers and student = 300 + 30 = 330
So, the total percentage of females in school = (176/330) × 100
= 53.33 %
Hence, the total percentage of females in school is 53.33%
问题18.阿曼的收入比阿尼尔少20％。阿尼尔(Anil)的收入比阿曼(Aman)的收入高多少百分比?
解决方案：
Let us take Rs 100 be the income of Anil
So, Aman income is 20% less than that of Anil’s income
i.e 100 – 20 = Rs 80
The difference in income of both Aman and Anil = Rs 100 – Rs 80 = Rs 20
So, Anil’s income is Rs 20 more than Aman’s income
And in percentage it will be (20/80) × 100 = 25 %
Hence, Anil’s income is 25% more than that of Aman’s income
问题19.机器的价值每年贬值5％。如果该机器的现值为100000卢比，两年后其价值是多少?
解决方案：
Given, the present value of machine = Rs 100000
Also, every year the value of machine depreciates by 5 %
So, we can say that the value of machine after 2 years will be 100000 × (100-5)/100 × (100-5)/100
= 100000 × 95/100 × 95/100
= Rs 90250
Hence, the value of machine after 2 years will be Rs 90250
问题20 ：一个城镇的人口每年增加10％。如果现在的人口是60000，两年后人口将是多少?
解决方案：
Given, the present population of town = 60000
Also, every year the population of town increases by 10 %
So, we can say that the population of town after 2 years will be 60000 × (100+10)/100 × (100+10)/100
= 60000 × 110/100 × 110/100
= 72600
Hence, the population of town after 2 years will be 72600
问题21 ：一个城镇的人口每年增加10％。如果当前人口为22000，请在一年前找到其人口。
解决方案：
Given, the present population of town = 22000
Also, every year the population of town increases by 10 %
Let a be the population of town a year ago
So, according to this the present population will be a × (100+10)/100
So, 22000 = 11a/10
a = 20000
Hence, the population of town a year ago is 20000
问题22：安吉特的工资增加了10％。他的新工资是卢比。 3575.他加薪前的工资是多少?
解决方案：
Given, Ankit has an increment of 10% on his salary
His new salary is Rs. 3575
Let a be the original salary of Ankit
So, according to this his salary after increment will be a × (100+10)/100
So, 3575 = 11a/10
a = Rs 3250
Hence, the salary of Ankit before increment is Rs 3250
问题23：在新预算中，汽油价格上涨了10％。一个人必须减少多少百分比的消耗，以使支出不会增加?
解决方案：
Given, the price of petrol rose by 10%
Reduction in the consumption so that the expenditure does not increase,
= (increase%)/(100 + increase%) × 100
= 10/(100+10) × 100
= 9.09 %
Hence, one can reduce the consumption of expenditure by 9.09%
问题24. Mohan的收入是每月15500卢比。他节省了11％的收入。如果他的收入增加10％，那么他的储蓄减少了1％，现在他存了多少钱?
解决方案：
Given, Mohan income is Rs 15500
He saves 11% of his income
So, the savings of Mohan = 11% of Rs 15500
= (11/100) × 15500
= Rs 1705
If his income increases by 10%, then new income 15500 + 10% of Rs 15500
= 15500 + (10/100) × 15500
= Rs 17050
Also, he reduces his saving by 1%, so now he saves 11 – 1 = 10 % of his income
= 10% of Rs 17050
= Rs 1705
Hence, the savings of Mohan will remain the same i.e Rs 1705
问题25.什卡的收入比沙鲁的收入高60％。 Shalu的收入比Shikha的收入少百分之几?
解决方案：
Let us take Rs 100 be the income of Shalu
So, Shikha income is 60% more than that of Shalu’s income
i.e 100 + 60 = Rs 160
The difference in income of both Shikha and Shalu = Rs 160 – Rs 100 = Rs 60
So, Shalu’s income is Rs 60 less than Shikha’s income
And in percentage it will be (60/160) × 100 = 37.5%
Hence, Shalu’s income is 37.5% less than that of Shikha’s income
问题26. 3500卢比应在三个人之间共享，以便第一人获得第二人的50％，而第三人则获得第三人的50％。他们每个人会得到多少?
解决方案：
Let third person will get Rs a
So, second person will get 50% of the third i.e (50/100) × a = a/2
Also, first person will get 50% of the second i.e (50/100) × a/2 = a/4
Sum of their money = 3500
So, a + a/2 + a/4 = 3500
a = 2000
So, third person will get = a = Rs 2000
The second person will get = a/2 = Rs 1000
The first person will get = a/4 = Rs 500
Hence, the first, second and third person will get Rs 500, Rs 1000 and Rs 2000 respectively
问题27.加价20％之后，中国花瓶的价格为2000卢比。该物品的原价是多少?
解决方案：
Let a be the original price of vase
Hike in the price of Vase = 20 %
So, price after hike will be a × (100+20)/100
So, 2000 = 12a/10
a = Rs 1666.67
Hence, the original price of the vase is Rs 1666.67