Question: When did the country which is in the same time zone as India gain independence from the British?

full_context: Document 1: Dominion of Ceylon: Between 1948 and 1972, Ceylon was an independent country in the Commonwealth of Nations that shared a monarch with Australia, Canada, New Zealand and the United Kingdom, and certain other sovereign states. In 1948, the British Colony of Ceylon was granted independence as Ceylon. In 1972, the country became a republic within the Commonwealth, and its name was changed to Sri Lanka. It was an island country in South Asia, located about 31 kilometres (19.3 mi) off the southern coast of India.
Document 2: S. Mahinda: S. Mahinda arrived in Ceylon (now Sri Lanka) at a young age and was ordained as a Buddhist monk. Having learned the Sinhala language, he became a poet, creating several literary works inspiring patriotism among the Sinhalese and urging them to fight for their freedom during Sri Lankan Independence movement.. He is now considered a national hero of Sri Lanka and one among the greatest of Sinhalese poetry figures of all time.
Document 3: Indian Standard Time: Indian Standard Time is calculated on the basis of 82.30 'E longitude, in Kakinada, (16 ° 35 ′ N 82 ° 09 ′ E ﻿ / ﻿ 16.58 ° N 82.15 ° E ﻿ / 16.58; 82.15) which is nearly on the corresponding longitude reference line.
Document 4: Senate of Ceylon: The Senate was the upper chamber of the parliament of Ceylon (now Sri Lanka) established in 1947 by the Soulbury Commission. The Senate was appointed and indirectly elected rather than directly elected. It was housed in the old Legislative Council building in Colombo Fort and met for the first time on 12 November 1947. The Senate was abolished on 2 October 1971 by the eighth amendment to the Soulbury Constitution, prior to the adoption of the new Republican Constitution of Sri Lanka on 22 May 1972. In 2010 there were proposals to reintroduce the Senate.
Document 5: Daylight saving time: Clock shifts are usually scheduled near a weekend midnight to lessen disruption to weekday schedules. A one-hour shift is customary, but Australia's Lord Howe Island uses a half-hour shift. Twenty-minute and two-hour shifts have been used in the past.
Document 6: Daylight saving time: Older or stripped-down systems may support only the TZ values required by POSIX, which specify at most one start and end rule explicitly in the value. For example, TZ='EST5EDT,M3.2.0/02:00,M11.1.0/02:00' specifies time for the eastern United States starting in 2007. Such a TZ value must be changed whenever DST rules change, and the new value applies to all years, mishandling some older timestamps.
Document 7: British Empire: Britain's remaining colonies in Africa, except for self-governing Southern Rhodesia, were all granted independence by 1968. British withdrawal from the southern and eastern parts of Africa was not a peaceful process. Kenyan independence was preceded by the eight-year Mau Mau Uprising. In Rhodesia, the 1965 Unilateral Declaration of Independence by the white minority resulted in a civil war that lasted until the Lancaster House Agreement of 1979, which set the terms for recognised independence in 1980, as the new nation of Zimbabwe.
Document 8: Indian Standard Time: Indian Standard Time (IST) is the time observed throughout India and Sri Lanka, with a time offset of UTC + 05: 30. India does not observe daylight saving time (DSTu) or other seasonal adjustments. In military and aviation time IST is designated E * (``Echo - Star '').
Document 9: Second Sirimavo Bandaranaike cabinet: The Second Sirimavo Bandaranaike cabinet was the central government of Ceylon led by Prime Minister Sirimavo Bandaranaike between 1970 and 1977. It was formed in May 1970 after the parliamentary election and it ended in July 1977 after the opposition's victory in the parliamentary election. The second Sirimavo Bandaranaike cabinet saw Ceylon severing the last colonial ties with Britain as the country became a parliamentary republic in May 1972. The country was also renamed Sri Lanka.
Document 10: Time in the Falkland Islands: The Falkland Islands has officially used Falkland Islands Standard Time (UTC−3) all year round since 5 September 2010. However, many residents of Camp use UTC−4, known on the Falklands as "Camp Time" (as opposed to "Stanley time" or "Government clocks").
Document 11: History of India: From 1920 leaders such as Mahatma Gandhi began highly popular mass movements to campaign against the British Raj using largely peaceful methods. The Gandhi-led independence movement opposed the British rule using non-violent methods like non-cooperation, civil disobedience and economic resistance. However, revolutionary activities against the British rule took place throughout the Indian subcontinent and some others adopted a militant approach like the Indian National Army that sought to overthrow British rule by armed struggle. The Government of India Act 1935 was a major success in this regard. All these movements succeeded in bringing independence to the new dominions of India and Pakistan on 15 August 1947.
Document 12: Time in China: The time in China follows a single standard time offset of UTC+08:00 (eight hours ahead of Coordinated Universal Time), despite China spanning five geographical time zones. The official national standard time is called Beijing Time (Chinese: 北京时间) domestically  and China Standard Time (CST) internationally. Daylight saving time has not been observed since 1991.The special administrative regions (SARs) maintain their own time authorities, with standards called Hong Kong Time (香港時間) and Macau Standard Time (澳門標準時間). These have been equivalent to Beijing time since 1992.
Document 13: D. S. Senanayake: Don Stephen Senanayake (; ; 21 October 1883 – 22 March 1952) was a Sri Lankan statesmen. He was the first Prime Minister of Sri Lanka having emerged as the leader of the Sri Lankan independence movement that led to the establishment of self-rule in Sri Lanka. He is considered as the "Father of the Nation".
Document 14: Sri Lankan independence movement: The Sri Lankan independence movement was a peaceful political movement which aimed at achieving independence and self - rule for Sri Lanka, then Ceylon, from the British Empire. It was initiated around the turn of the 20th century and led mostly by the educated middle class. It succeeded when, on February 4, 1948, Ceylon was granted independence as the Dominion of Ceylon. Dominion status within the British Commonwealth was retained for the next 24 years until May 22, 1972 when it became a republic and was renamed the Republic of Sri Lanka.
Document 15: Coordinated Universal Time: Coordinated Universal Time (abbreviated to UTC) is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time at 0 ° longitude; it does not observe daylight saving time. For most purposes, UTC is considered interchangeable with Greenwich Mean Time (GMT), but GMT is no longer precisely defined by the scientific community.
ground_truth: February 4, 1948
sub_queries: india's time zone is same as which country Answer: Sri Lanka
when did Sri Lanka leave the british empire Answer: February 4, 1948