RPF 11 Jan 2019

Average weight of 89 Notebooks in a box = 8.9 kg

=> Total weight = $$89\times8.9=792.1$$ kg

Let weight of new book = $$x$$ kg

=> New average = $$\frac{792.1+x}{90}=9$$

=> $$792.1+x=90\times9=810$$

=> $$x=810-792.1=17.9$$ kg

=> Ans - (C)

Let number of 1 rupee, 5 rupees and 10 rupees respectively be $$3x,5x$$ and $$7x$$

Total amount = $$(1\times3x)+(5\times5x)+(10\times7x)=2450$$

=> $$3x+25x+70x=2450$$

=> $$x=\frac{2450}{98}=25$$

$$\therefore$$ Number of 10 rupees coins = $$7\times25=175$$

=> Ans - (B)

Marks obtained = 79 + 95 + 31 + 35 = 240

Maximum marks = 120 + 130 + 70 + 80 = 400

$$\therefore$$ Overall percentage obtained by him = $$\frac{240}{400}\times100=60\%$$

=> Ans - (D)

Average weight of first 4 bangles = 72 grams

=> Weight of first 4 bangles = $$72\times4=288$$ grams

Similarly, weight of remaining 6 bangles = $$73\times6=438$$ grams

$$\therefore$$ Average weight of the total bangles = $$\frac{288+438}{10}=72.6$$ grams

=> Ans - (C)

Given : $$x=0.128888$$

=> $$100x=12.8888$$ ------------(i)

=> $$1000x=128.8888.....$$ ------------(ii)

Subtracting equation (i) from (ii), we get :

=> $$900x=128.8888-12.8888=116$$

=> $$x=\frac{116}{900}$$

=> Ans - (B)

ABCD is the table and the glass piece is placed inside.

Side of glass = $$\sqrt{961}=31$$ cm

Width between glass and table = $$11$$ cm

=> Side of table = $$11+31+11=53$$ cm

=> Ans - (A)

Let modest price = Rs. $$100x$$

After 1st discount of 10%, selling price = $$100x-(\frac{10}{100}\times100x)=Rs.$$ $$90x$$

Similarly, after 2nd discount of 20%, selling price = $$90x-(\frac{20}{100}\times90x)=Rs.$$ $$72x$$

According to ques, => $$72x=1836$$

=> $$x=\frac{1836}{72}=25.5$$

$$\therefore$$ Suppression price = $$\frac{50}{100}\times100\times25.5=Rs.$$ $$1275$$

=> Ans - (C)

Rate of interest = 6% and time period = 2 years

Let principal sum = Rs. $$P$$

Also, difference between compound interest and simple interest for 2 years = $$P(\frac{r}{100})^2$$

=> $$P(\frac{6}{100})^2=198$$

=> $$P=198\times\frac{10000}{36}$$

=> $$P=Rs.$$ $$55,000$$

=> Ans - (D)

Speed of train = 54 kmph = $$54\times\frac{5}{18}=15$$ m/s

Let length of bridge = $$x$$ m

Using, speed = distance/time

=> $$15=\frac{145+x}{29}$$

=> $$145+x=29\times15=435$$

=> $$x=435-145=290$$ m

=> Ans - (D)