# F3 Math Problems

1)The memory capacity of the harddisk in Bruce's computer is 8.5(10^8) B (B = byte). The files stored include:

Types of files Space occupied (B)

Operations System 3.3(10^8)

Word Processing Programs 8.4(10^7)

Internet Browsers 2.5(10^7)

Graphical Files 8.2(10^6)

Text Files 1.6(10^6)

Other Software Programs 3.0(10^8)

(a) How much space is left in Bruce's harddisk?

(b) Bruce sends his text files to David by e-mail .It takes 2.1(10^-5) second to send all the text files to David?

2) Mr and Mrs Chan are an old couple. Their ages differ by 1. If the sum of their

ages is represented by a binary number,then all digits of this binary number are. 1. Find their ages.

NEED STEPS, PLZ!!

Rating

(1)

(a) Capacity occupied = 3.3(10^8) + 8.4(10^7) + 2.5(10^7) + 8.2(10^6) + 1.6(10^6) + 3.0(10^8) = 10^6[ 330 + 84 + 25 + 8.2 + 1.6 + 300] = 748.8(10^6)

So space remaining = 8.5(10^8) - 748.8(10^6) = (850 - 748.8)(10^6)

= 101.2(10^6) or 10.12(10^7) or 1.012(10^8).

(b) Speed of the computer is unknown, so cannot calculate the time.

Assume speed to be S byte per second.

So time required = 1.6(10^6)/S second.

(2)

If all the digits are 1, the sum of their ages must be

1 + 2 + 4 + 8 + 16 + 32 + 64 = 127 ( the next digit is 128!!)

so their age is (127 - 1)/2 and (127 - 1)/2 + 1 = 126/2 and 126/2 + 1 = 63 and 64.

• Login to reply the answers